Through the National Arbitration Forum, Microsoft has won the rights to a series of Xbox-related domain names formerly owned by Cheng Juan of China. The disputed domains include things like xboxcompanion.com, xboxlivetv.com, xboxphone.com, and xboxtablet.com, but also xbox8.org and xbox8.us.
Microsoft was likely most interested in regaining these just to protect its own IPs – and the immediate use of things like xboxlivetv.com and xboxphone.com seem apparent.
It's tempting to suspect Microsoft is eyeing "Xbox 8" as the next console name due to the two domains that reference it; however, Microsoft already began integrating Xbox Live, and the "Xbox" name, into all its consumer products, including Windows 8. Also, it would be really weird if a domain squatter guessed the name.