I read that "MySpace Unblocks User-Generated Videos Hosted on Photobucket" and couldn't help but recall a meeting I sat in on in 2001 when I was working at the FCC's Office of Plans and Policy. Cable and Wireless was talking about some really cool fiber multiplexing technologies, and also addressed their decision to de-peer PSINet.
It occurred to me that another sign of the 'net evolution is that interconnection of web services has replaced the interconnection of backbone networks. MySpace flexing its pageview-driven market power doesn't seem so different.
There is a great working paper on peering agreements in the OPP white paper library [pdf link].