Yep, I had the same problem as sfraize - exactly. Address Book showed in the Dock as being active, but didn't display, and wasn't showing in the Force Quit window either.
Here's what I did:
1. removed Address Book from the Dock;
2. tried to launch it from the Applications folder (but it crashed the Finder and I had to shut down by holding the Start key);
3. on reboot, launched Address Book again from the Applications folder and this time, magically, it worked;
4. I've now put it back into the Dock, from where it seems to launch just fine.
Hope this helps people with similar problems!
I really don't like this horrible leather-effect-torn-pages appearance of the OS apps, by the way. About as progressive and witty and elegant as printing CDs with images of vinyl records (anyone else remember World Party's 1990 album Goodbye Jumbo?)