This is something I would integrate myself if I had the time, but I was wondering if vbseo has ever thought about using Yahoo's API for Update Notification?

Site Explorer Documentation for Yahoo! Search Web Services

It should be a fairly simple thing to ping the YUN after each new post (in a public forum) or new thread. Since each IP is allowed 5,000 pings per day, it would be valuable for all but the very largest of sites.

Anyway, just curious.