The new page will live stream the actually address as well as show social media happenings during it. Also right after the address White House staffers will be online hosting a Live Chat on the site answering questions (that's pretty awesome!).
The following two days also have some awesome things coming from that page. On Wednesday Robert Gibbs will answer questions sent to him via twitter. Thursday people will get a crack at the President himself when Obama logs in for a Live Q&A through youtube. Later Thursday policy experts will host a live round-table.
This site is probably worth hitting between Tuesday and Thursday with all the cool stuff they are doing.