I'm trying to find out if SitePoint developed their RSS feeds in-house or if they are something they were able to create with some features of vBulletin. I'll post any information I find out about that.
I created some RSS feeds for my website just a couple of weeks ago, and I was amazed how quickly I was able to do that, given that I didn't know a thing about how to create them before I started.
This is just one of those things I'd like to see added as a forum feature in your "spare time."