Microsoft's server and tools unit has proved they can take something like Web 2.0 and make it easier to program for. It has a very viable business model there.
There have been real attacks; this is not theoretical. All you have to do is go to an evil Web site or click on a link in an e-mail and some hacker dude owns your computer.
If you look at Microsoft's two biggest businesses, Windows and Office, they don't have an obvious Web 2.0 play. But the server and tools business at Microsoft has a vested interested in making Web 2.0 work, and they have a strategy to do it.