You saw our complete Zune guide yesterday, but what you didn't see was the Zune Social—which didn't go up until today! The social is pretty much Facebook for music (and only music), and displays the stuff you and people on your list have listened to on their Zune players. It really helps your enjoyment if you've got more than one friend who has the Zune, which is probably the point.
Sending messages, browsing other people's music history, and listening to 30 second samples are super easy to do. If you've got a Zune Pass subscription, you can pretty much go nuts looking at other people's songs and downloading them directly to your player in a sort of crazy music buffet. The most interesting thing we found is that both "Zune" and "Microsoft" are restricted words. You can't have them as your "status" message if you wanted to say "Testing out the Zune". All in all, it's a pretty good start (the site's still in beta) to the internet social aspect of the Zune that Microsoft is trying to expand on. [Zune]