Via freshmeat, RSS Mix Tape:
RSS Mix Tape reads items from specified RSS feeds and displays them in a list. Selected posts can be categorized and commented on, and an RSS feed is generated for each category. It also supports LiveJournal input whether or not you are a paid user.
In short, RSS In, RSS Out.
It runs with Python, PyQT, PyKDE, and xmlbase. Of course, OPML would probably be the format of choice for containing a list of feeds, though I understand the want for RIRO (RSS in, RSS out). I don’t know how easy it would be to have the commentary in OPML.
If anyone has an RSS mix tape feed that they update fairly frequently, I wouldn’t mind checking that out.