An update on Xbox LIVE's Major Nelson's Blog has word on how Xbox LIVE will operate under Windows 8. Some of the details on this still remain to be explained, but here's the overview from the good major:

We are confirming that we will be bringing Xbox LIVE to the PC with Xbox LIVE on Windows. We are very excited about Xbox LIVE coming to Windows 8. Xbox LIVE brings your games, music, movies, and TV shows to your favorite Microsoft and Windows devices. Bringing Xbox LIVE to Windows 8 is part of our vision to bring you all the entertainment you want, shared with the people you care about, made easy. At BUILD we are showing that it is easy for developers to create games for Windows 8 that take advantage of the power of Xbox LIVE. We have much more detail to share about the capabilities of Xbox LIVE on Windows and look forward to the opportunity to do so in the near future.

If you want to learn more about Windows 8, you can watch the Keynote from earlier today.