If you were at the Microsoft Professional Developers Conference 2008 (PDC2008), you got a copy of Windows 7 pre-beta to install. However, if you installed it, you might have been upset to find that a lot of the cool features shown in the keynote address were disabled. I'm not sure why Microsoft did this but Rafael Rivera, Jr. has hacked the features back on. I am not a fan of nasty hacks like this but it is pre-beta software after all.
Jump to Rafael's blog post to download the tool and read the instructions.