You know, I've been looking for something that does the same thing because I've got to keep up with 5 different email lists and they'd be easier in a forum.
Here's two sites I've noted down to try:
http://www.mail2feed.org/
http://www.reblinks.com/
Let me know how it goes! Specifically, I'm looking to see if either one is just posting the summary. That would be useless to me (and probably you).