What's interesting here is the team will be forcing IE7 installs out through normal Automatic Updates - overwriting your IE6 overnight.
That's both impressive, and a bit scary at the same time.
You can read more about the IE Team's launch here at their blog.
I for one am all for this! I've been using IE7 since Beta 2 (beta 1 was aweful buggy), and now been designing most client projects at Telligent under IE7 (which renders fine under FF). But IE6 has had some issues.
So I for one welcome this update.