Apple's WWDC Keynote kicks off at 10am PT, 1pm ET.
Apple's press release revealed their talking points: MacOSX 10.7 Lion, iOS5, and iCloud.
Apple has gone out of it's way to make sure people know this is a software focused event, and with the above to discuss, I'd be surprised if it's less than 2 hours. There has been some speculation about a new TimeCapsue, which will integrate with whatever iCloud turns out to be, but this is all base rumour at this stage.
There hasn't been any announcement of a live stream of the keynote, but Apple doesn't typically give much notice. So we may still see it in the next few hours [if at all]. Otherwise, I've typically found the best live-blogs to be: