http://www.xe360.com/forums/showthread.php?p=1115#post1115
First feature: You know how Halo 2 has XML feeds of your stats, and how you can put them into certain XML readers? That idea wasn't just for Halo 2--it was more of a test of the XML/RSS feeds. Within the next year every game from Activision, EA, Microsoft, pretty much everybody will put stats into a unified RSS feed for each person's gamertag. These feeds will be read on Xbox 360, MSN Messenger, a RSS program, Windows Vista, or online at certain game sites (perhaps XE).
Second feature: MSN Messenger will be in 360--that is right, the 360 will have MSN Messenger, maybe not out of the box but it will have it. Rumor has it also Microsoft is working to get AOL to make a version of AIM for Xbox 360. So not only can you be playing games on 360, you can also talk to your buddies online in between sessions.
Third Feature: How will you type back to people on Messengers though? That part is easy--specially made Xbox 360 Keyboards and Mouse. The Keyboard and mouse will come in two flavors--wireless or USB. The Wireless ones will use the 360's special signals, and you basically would have to buy the combo, which should cost abou $50 total. the wired one may need a special keyboard, or you might be able to use your own keyboard and mouse.
Fourth Feature: Downloadable music service. MS is working on creating downloadable music service, and the service may actually prevent people from putting pirated MP3s on the system but it is unclear how they would do that.