Find here Dave's RFC, Q&A and a question.

Currently we are using OPML to distribute topics (OPML file) to users of the application we are developing, K-collector. Not sure about mySubscriptions, but if myPublicFeeds.opml would support hierarchies we could publish an opml index of all topics managed on our servers with links to topics' rss feeds organized by classification (Who, What, Where, When, etc.). It would make a lot of sense, I like this idea.

Consider it implemented as soon / if as the specs are defined.

Post babes, get flow. :-)