VP responsiveness
One of the things I really like about the community aspect of Microsoft is that it's given hooks a long way into Microsoft.
For example... some of you might've watched the video from Channel 9 featuring Chris Jones. Chris Jones is a corporate vice-president. He's in the Executives list. But in the video, he said something like "If you have any feedback about Vista, then drop me a line..." So I did. I said there should be a really obvious way of activating Vista (proactively, rather than just reacting to a popup in the taskbar), and a really obvious way of telling if Vista has been activated (like in the "Registered to:" section of System Properties).
And he got back to me within a day, and now we've exchanged a couple of emails about it, and he's suggested a new feature to one of the guys in his team.
I'm sure that a couple of years ago, this wouldn't've been nearly so possible. I'm not on any beta-testing list or anything - it was just that I had watched a video (well, had it on in the background while I was doing other stuff), and decided that I should give a bit of feedback. I could've gone hunting for an official beta-feedback address - but this was easy. Chris could've just pointed me at an address, or could've just ignored me. But he didn't. I like that. :)