Google's success has a downside--a lot of enemies. Beyond reflexive contrarians who hate Google because they enjoy swimming against the currents of popular culture, beyond governments around the world that prefer limited rather than universal information access, there are many businesses that feel threatened by the scope of Google's ambitions.

Could Google really fail?"People underestimate the degree to which other companies feel threatened by Google," says Donald Leka, CEO of Internet media sharing company TransMedia. "While Google is trying to sell products to these companies, they're also competing for eyeballs."

(Leka's company, not coincidentally, has been shopping the upcoming revision of its Glide Effortless online media sharing environment to companies eager to attract some of the eyeballs tuned to Google.)

Google's power as a source of traffic and revenue for many online companies represents a potential vulnerability. Startups have to convince investors that Google won't move into their market. Companies in those markets already have the same worry. Businesses that depend on Google realize the risk of dependency.

ISPs envy the traffic and user loyalty that Google, not to mention Microsoft and Yahoo, have been able to secure. Caught flat-footed by the rapid shift toward software-as-a-service, they're struggling to add value to commodity Internet access. Online software is one way to do that, but they're only just realizing how far behind they are.

Deals like the one between AT&T (SBC) and Yahoo represented an effort to wed Internet access with online content and services, but such arrangements only represent a short-term fix. At the end of the day, Yahoo users don't much care whether they get Internet access from AT&T or somewhere else. They care about Yahoo because Yahoo has their vacation photos and e-mail.

Publishers don't much like Google either, despite the arguable benefits of making texts available and searchable online. In fact, a great many people have particular sets of information they would rather not see online--witness the Internet filtering industry.

The point is that Google is different. It represents a change in the balance of power, and that scares a lot of people. To some degree, they would like to see Google fail.

Below, in no particular order, are a few potential stumbling blocks for Google.

Growth Like many successful companies, growth represents a challenge. Large companies move slowly, and cutting-edge ideas tend to get dulled by committee. As Google continues to expand, it will be tested. As Google SVP of Operations Urs Holzle said in an e-mail interview, "For as long as I can remember, organizational growth has been the #1 issue [at Google]."

Risk: Minimal. At least for the next decade, Google should be able to navigate the organizational challenges of growth. Because the company has chosen to pursue an inherently interesting set of computer science problems, it should have no trouble attracting and retaining top talent.

Microsoft Microsoft hasn't yet found a way to fit the traditional software business into the new reality of online software-as-a-service. But if the company has the courage to open up and minimize the resentment-inducing business practices that stoke discontent among its partners, it stands a fair chance of beating Google at its own game. It has the money and talent necessary to compete.

Risk: Minimal. Microsoft wants to change, but to do so it must give up its monopoly on the desktop and lower prices. Stockholders don't like that.

Distributed Databases Search, at the moment, works best with a centralized index. That may not always be the case. Peer-to-peer networking and distributed database projects like the Information Commons may obviate the need for a centralized system.

Risk: Moderate. Efficient peer-to-peer searching requires significantly faster network infrastructure than currently exists--Google built that infrastructure from scratch, and it will retain that advantage for some time. But it makes much more sense for companies to control their databases than to rely on Google's index as a pointer to their data. If the trend is truly toward disintermediation--removing the middleman--then Google has to think long and hard about how far into the future it can play that role.

Net Neutrality Everyone wants a piece of Google's pie--ad dollars--and the companies that own the Internet's pipes may well get the government's blessing to help themselves. If it becomes acceptable to discriminate against certain kinds of Internet traffic, such as VoIP calls or video, companies that play in the VoIP and video space are going to be tempted to extract tolls from others using their pipes for competing services.

Risk: Moderate. Google may well have to partner with companies like AT&T to keep its traffic in the fast lane. It may end up looking a lot more like Yahoo in the future, with lots of content and distribution partners.

Energy Energy costs could skyrocket. Whether it's the prospect of nukes in the Middle East or dwindling worldwide oil supplies, it's easy to worry about the price of oil. Because the price of oil affects the price of electricity, it may be that in the future, vast server farms no longer make sense.

Risk: Minimal in the near term. There's too much money to be made on oil for a catastrophic Middle East conflagration. Energy will remain costly, but not prohibitively so. Ask again in 20 years.

The Law Technical innovation can't always trump legal tradition. Those that make money off intellectual property--copyrights in particular--remain fundamentally opposed to Google's mission to make information universally accessible. Unless Google can drive legal change alongside technical innovation, its future is likely to be determined in the courts. To date, Google has plowed ahead on interesting initiatives like its book scanning project with the notion that it's better to seek forgiveness than to ask permission. It may not be able to keep that up if it starts losing in the courts.

Risk: Moderate. Now that Google takes the idea of lobbying in Washington seriously, it should have the ability to push back against potential laws that might hinder its ability to operate. The telcos aren't the only ones that can play that game.

Trust All it takes is one disaster like AOL's release of search terms from hundreds of thousand of users to damage a company's reputation. Google could face a similar debacle.

Risk: Minimal. Google certainly takes such risks seriously. Given that it was the only company to resist when the U.S. Department of Justice came calling for search data, Google clearly is attuned to the privacy implications of the world's information.

Advertising Perhaps the biggest risk to Google is its reliance in clicks. Google sells clicks, and lots of advertisers buy them. The problem is that most don't want clicks; they want sales.

The cost-per-click model forces advertisers to gamble. But gambling is foolish unless the odds are in your favor. And few advertisers really understand the odds of turning a click into a sale. Add to that the potential for click fraud and you have a situation where alternatives start to look appealing. Cost-per-action advertising is one such alternative. It's a lot more attractive to advertisers, who only pay when a product is sold, and a lot less attractive to Google, which collects money on cost-per-click ads regardless of whether the click converted to a transaction.

Risk: Moderate. Now that eBay is forging ahead with cost-per-action ads, Google has to be ready in case advertisers tire of buying clicks. Google is experimenting with CPA-based ads, but if change does come, it will probably hurt the company's revenue.

Boredom Lastly, there's always the chance Google could become uncool.

Risk: You never know.