Out with the old and in with the new. Though thankfully for legacy users who don't particularly like change, you can revert back to the old interface which gives you your contact list and nothing else. However, it is quite handy seeing updates from your friends, yet those not equipped with the knowledge of the Zune/Windows Phone 7 user interface may be confused.
To see a brief review of the new Windows Live (Wave 4) applications, visit the iGeneration blog.