Business social networking site LinkedIn is going to be following in the footsteps of Facebook by opening up APIs over the next several months. Facebook's move has bolstered already skyrocketing membership and led to a ton of new applications. But what does this big step mean for LinkedIn and for social networking in business? Just like everything else in the Enterprise 2.0 world, business social networks won't get used unless they can do something better than e-mail and other apps.Opening up APIs lends some credibility to something that's heretofore often used for casual browsing and little else. That's because it could turn LinkedIn into a feature of another app, whether it be Salesforce.com or maybe Monster.com, or it could turn information feeds from those apps into Web parts that could be plugged into LinkedIn. The big lesson of the software world in general is to build a developer ecosystem. That's what's driven Microsoft. On the Web, that's increasingly done through opening up APIs, which have recently driven Facebook and Google Maps.

Despite writing two related blogs and mentioning the API plan in an interview last week, LinkedIn still declined to comment on what it meant for the company when I called to ask. "We'll have something to say in the near future," a LinkedIn spokesperson said. "We weren't ready to really announce anything." I'll take a stab at it myself, with a little help from the blogosphere.

LinkedIn's director of product management, Lucian Beebe, hints in a blog that the first scenario, LinkedIn as a feature, might be the most powerful. "LinkedIn APIs will let developers build applications that integrate with LinkedIn so you can access your LinkedIn network and profiles while you use that application," he writes. For example, a developer might create an app that finds LinkedIn connections you have at companies offering jobs on Monster.com or even be a source of resumes to Monster.com. Another app might integrate LinkedIn with a CRM app by color coding CRM contacts who are also on LinkedIn, maybe to show who is an important contact versus a peripheral one.

The second scenario, adding apps to LinkedIn, is just as interesting. If members could post links they find insightful via a deli.cio.us plug-in, for example, using LinkedIn as an expertise finder could be much more valuable because a profile might contain not only curriculum vitae but links to relevant information. Read/WriteWeb suggested an app that could show your contacts how the relative strengths of your relationships are with other contacts by surfacing stats like the number of times clicked on another profile. LinkedIn competitor VisiblePath already does this with an Outlook plug-in that tracks interactions. Still, more power plus more surface area is but a step.

Simply opening up APIs does not make LinkedIn equivalent to Facebook. LinkedIn profiles are static and don't create a dynamic network. Everything on my Facebook profile is linked. If I indicate I'm a fan of "Ender's Game" and have joined a larger network of people who live in Baltimore, clicking on "Ender's Game" in my profile automatically populates a group of like-minded Orson Scott Card fans in the city. Imagine doing that with professional interests. Likewise, I can set presence in Facebook. My Facebook presence currently says that I'm "working on a couple of stories." No such feature in LinkedIn. There are several other features like that; I won't go through them all here.

This move also does only a piece to make LinkedIn readier for integration with enterprise apps. It's fine to allow LinkedIn to become a sort of plug-in for Salesforce or Microsoft Dynamics or whatever, but plugging enterprise data into LinkedIn in applet form represents something that will surely perk up the ears of security folks. Controls are necessary to make sure that data doesn't escape its sandbox into the wilds of the Web.

Finally, what will make LinkedIn better than e-mail? That's the challenge I hear time and again when I talk to enterprise IT folks about Enterprise 2.0 technologies. I'm not sure there's an answer to that yet, but clearly there's a change afoot. UC Berkeley data recently showed that 6% of all its university e-mail traffic is actually from Facebook, and the only time I get Facebook e-mail (which I can turn off, as many people do, so the number could be much higher) is when someone posts a comment about me or requests me as a friend. There's more to Facebook than just those things, so that stat is somewhat astonishing to me.

Maybe LinkedIn has a chance. That's if it doesn't get supplanted by Facebook first, and I'll go into that in an article soon.