Microsoft: $252.82 billion IBM: $169.86 billion Google: $156.69 billion Apple: $155.37 billion
How did little Apple get to be neck-and-neck with mighty Google, the superstar of Silicon Valley? You can have your favorite theory... but I have three, which I believe combine to tell the story.
1. Selling stuff to customers makes more money than giving stuff away to customers.
With Google, just about everything a consumer wants is free free free. Free email. Free online application. Free maps. Free analystics. Free financial data. Free photo editor. Free desktop software. Free blog engine. Free YouTube videos. Free Free this. Free that.
By contrast, Apple don't give nuthin' away. No free email  MobileMe costs $99/year. No free music. Just about the only applications that are given away are players, like QuickTime and iTunes, which are tied to non-free products.
2. There are limits to what you can achieve by selling advertising, but there are no limits on what you can do by selling products.
Google sells ads, while Apple sells iPods. Google sells ads, while Apple sells Macs. Google sells ads, while Apple sells iPhones. Google sells ads, while Apple sells software. Google sells ads, while Apple sells music. Google sells ads, while Apple sells movies. Google sells ads, while Apple sells service contracts.
3. A charismatic leader adds a lot of value.
Apple has Steve jobs, the ber-CEO, the ultimate spokesperson, The Man in the Black T-Shirt. The only person comparable to Jobs is Microsoft's Bill Gates, who recently stepped down but was replaced by the nearly equally well-known (and much louder) Steve Ballmer.
IBM had a public face in Lou Gerstner, but Sam Palmisano keeps a much lower profile. Similarly, Intel had a great spokesman in the always-paranoid Andy Grove, but Paul Otellini is much less visible.
What about Google? The big dudes are the founders, Sergey Brin and Larry Page, and the rocket-scientist CEO, Eric Schmidt. All three are bona-fide geek gods  but they're not household names to consumers. In fact, one could define a geek as "someone who can name the three top guys at Google."
What's your theory? Why has Apple caught up to Google  and is it going to last?