Not sure if this is a first, but neat idea:  BBC plans to simulcast of its Radio 1 Big Weekend Music Festival this Saturday inside the popular online/avatar game Second Life.
BBC has “bought” a virtual tropical island within the Second Life world, and the radio network believes up to 400 people will be able to attend the event with admission controlled by computerised bouncers. All visitors to the island will be issued with a virtual digital radio that will allow them to listen to Radio 1 long after the event.

Besides this, Radio 1 plans to use the island to debut new bands over the next year.
Last year, BBC’s new program Newsnight presenter Jeremy Paxman and business correspondent Paul Mason broadcast TV’s first ever face-to-face studio session from inside the game.
Online, Radio 1 will also be webcasting the program on its site here