There are four lists currently and my understanding is that they plan to expand the number greatly in the near future. The current Lists:
The feeds from each list are availabe in opml format, and they’ve created an aggregate RSS feed for each list as well.
This is a great example of Reading Lists – edited, dymanic opml feed lists. It can also be compared to Technorati’s Blog Finder, which ranks related feeds as well. The difference is that Technorati relies on publisher tags to determine content topic for a blog, whereas Pubsub relies on a human expert to determine which feeds should be included.
See Library Stuff for more information. Steven Cohen, who writes Library Stuff, is PubSub’s Senior Librarian.