Well, Nintendo has launched the official website for e3 for botht the Cube and GBA, and Sony has the PlayStation 2's e3 page up as of now, there doesn't seem to be an Xbox e3 site up, but I'm sure it's coming especially since Microsoft has the first conference.
Anyhow, both sites look nice, I prefer the look of the PS2's site for some reason, both are pretty barebone at the moment which just some general information on the show, some games, some screens and that's about it. Look for them to have media and more games in the coming days.
http://e3.playstation.com/
http://www.nintendo.com/e32k3/