I was looking for such a thing tonight and ran across this AppScript trick http://www.crossbrowser.net/290/using-friendfeed-to-automati...

It's less likely to be blocked by Twitter because you have to register and use your own client ID. I couldn't get it to work for some reason, though.

I was installing because there are a ton of tools that rely on Twitter RSS, e.g. to auto-post to Facebook and the like. Those are broken now.