Were you curious as to how many people who are on Xbox 360's Live services subscribe to the Gold services? About half according to Microsoft's Dennis Durkin
, who is the head of Microsoft's Interactive Entertainment Business. That's 12.5 million people who pay for the privelage to play other people, use Facebook, Twitter, and other Gold member services. He also gives a stat that 40% of the time online is spent on aspects of Xbox Live other than gaming.
At the current rate of $60 a pop, we're talking a good $750 million in revenue a year from just that area. Add in all the little things you can spend money on and you get a good chunk of change going into Microsoft's pockets. Of course, a lot of that also goes to paying for many of the contracts, hardware, and support needed to keep the service running.