It's a fork I started in 2005. I wanted to make improvements to the environment without the intense discussions that were taking place on the kernel mail list.
I've done a lot of work since then, fixing bugs, rewriting modules that needed rewriting, and adding lots of new capabilities and connections to web services, like Amazon, Twitter, Flickr, OAuth. There's JSON parser. The RSS support is much deeper and simpler. Etc.
There are a bunch of new apps, including Radio2 which is a linkblogging tool, River2 which is a river-of-news aggregator and World Outline which is a new content management system built around outlining. (The site you're reading right now is a worldoutline-managed site.)
This site points you to places to look for new stuff.
PS: This is a work in progress. So the lists aren't complete. Working on it! :-)
river2.root is a rewrite of the aggregator that shipped with Frontier/Radio for years. It needed a rewrite, since we learned a lot about RSS over time. It is a podcatcher, does realtime with the RSS cloud element.
scripting2.root is a rewrite of the blogging software I use for scripting.com. You can install it and run it. It also need a rewrite, as it had evolved over years with lots of additions and trial features that didn't pan out.
radio2.root, as its name implies, is a link-oriented group linkblog app. It's the blogging portion of Blork. I know that's confusing but that's the way the product came together. You can find instructions on setting up a blork server on the frontiernews site.
myPhotos.root downloads all your pictures from Flickr and uploads them to S3. Leave it running and you'll have copies of everything you flow through Flickr.
html.directory, rebuild, and streamline. Directories in Manila won't work with this version.
mainResponder used to be in a separate root, now it's in opml.root at builtins.mainResponder. Tools websites are managed by mainResponder now, the websiteFramework responder is still an option, but not the default.