The Kojima Productions Special Site for E3 2012 is now up. Strangely enough, there only seems to be a Japanese version, at least for now. On the site, you can watch all the videos from the pre-E3 conference, as well as some additional footage such as the intro for Zone of the Enders HD Collection. The videos are in Japanese though, and no subtitles are available at this point.
The official Japanese Metal Gear Rising site has been updated as well.
It is likely Kojima Productions will keep updating the site throughout E3. GTTV will feature a live demo of Metal Gear Rising: Revengeance on June 4th, and the game will be playable on the show floor.