At precisely 12:01 pm EST today, the new www.whitehouse.gov went live. Even though he hadn't yet said his oath, that's the moment Obama's presidency officially began.
The new site looks very modern and the heart of the content is the new White House Blog. It's called The Briefing Room and it's all about keeping American citizens, and the rest of us, in the loop. You can even subscribe to the RSS feed at http://www.whitehouse.gov/feed/blog.
I'm super biased, but I think a blog is a fantastic tool for the President and his administration to connect with the rest of the nation and the world. There are no comments accepted, I can imagine moderation would be a nightmare, but it is a new age idea from the first Internet Prez.