While I haven't had a chance to do any of the sessions on the site, I have been participating in another online conference over the last few days which I think is the same kind of experience. The librarians at the school and I have been a part of an online conference through Your School Library called E-Book Futures. The format is usually a VoiceThread presentation that we can post to as well as a discussion board for each one.
The thing that I find most helpful is the discussion boards, because that is were we as librarians really begin to hash things out. What is possible and what is note. What works for this library even if it may or may not work for another. The conference as a whole is giving us a much better understanding of ebooks and libraries, where we stand now and what we should be doing in the future.
The hardest part about the online learning, is time! Unlike a conference you go to in person, you don't have a designated time to be there and it's easy to not get around to it. There is so much available that you can see and read, but when you are still working full time how will you get to it all?
The thing that I'm most excited about it knowing that this resource is available to both me and my colleagues. It's the perfect thing to share with others when they need just a little bit of PD in an area. It's also great to share with administrators who need to understand more about where you are coming from.