I just ran across a interesting blog post today that talks about a bit about some of the differences between Google and Microsoft.
Having been around the block a few times I too know many folks who have found their way to Google, back when I lived in the bay I knew a few folks who were early Googlers, these folks loved their jobs, had a ton of influence and are now, well filthy stinking rich (and I am happy for them, if not also a bit jealous!)
With that being said that can probably be said for most anyone who is earlier enough at successful startup, that being said Google is so far away from being a start-up now that this is not how you should measure the company from a career standpoint.
Of the folks I know who have ended up at Google, on average I find the more junior people love it there, its unstructured, and all of their needs are taken care of, much like they are still in school. The more senior folks typically have an allergic reaction to the environment, this blog post and the quotes in it are fairly consistent with the sort of message I hear from these sorts of folks who end up at Google.
That's not to say Microsoft is perfect, or that there are not examples of senior folks acclimating to the Google environment (from Microsoft or other companies) its just that through my unscientific observations it seems that this is a trend, one that I would love to hear your opinion on.