Wendy Grossman mentioned this in her last column, but whether you're into sport or not, the technology underlying the multicast is pretty interesting.
See Morality plays.
Due to rights problems, the Olympics coverage is restricted to people in the UK, but after the Olympics the techies at the BBC are going to look at international delivery.
Currently, the multicasting continues of five streams at 370Kbit/s, while unicast streams are 225Kbit/s.
The BBC techies are hoping to involve more ISPs in current and future plans for multicasting, according to the techie site, here. ยต