MSN spaces is now live. I guess it's been in beta in Japan for a while, but now it's available more widely. Dare Obasanjo, the author of RSS Bandit recently joined that team and has a good entry on MSN spaces. It lets you create a personal "space" where a blog is just one of the many things you can do.
A beta of MSN Messenger 7.0 is also available at http://messenger.msn.com/beta. It has spaces integration along with more emoticons, winks, and nudges.
The spaces server seems a bit overloaded right now. I guess everyone is signing up :-)
Update: The Messenger link above doesn't seem to be valid (yet?). Sorry about that.