Microsoft is taking requests for folks who want to beta test a connector to Xbox Live via the PC. In the request it asks:

"Are you interested in being part of a select group that is invited to help beta test a new service that lets PC game players connect with their friends on the Xbox through the LIVE gaming network?"

This has been posted on the Internet over the past few months, at least now we know it is going to beta and should be released to the world shortly after that. We'll be watching for more information, and hopefully participate in the beta test.