Last week I gave a talk on peer learning with Ben Vershbow of NY think-tank if:book. He's been doing some fabulous things in collaborative reading, which I think could have big implications for the way blogs and discussion forums interact. If:book have developed a hack for the Wordpress platform which places comments to the right of each paragraph of a blog post. It's based on marginalia in old-fashioned academic texts and is intended to allow collaborative annotation of academic texts - but it's such a simple tool that I think it's got much wider implications.
We've been playing with an installation of the system based on the talk we gave at www.futureofthebook.org/freeschool, with some success.
The software itself is available for free at www.futureofthebook.org/commentpress. I strongly urge you to check it out and put it to good use!