Twitter has patent for "pull to refresh" MAR 27 2012
Loren Brichter invented the "pull to refresh" interface mechanism for Tweetie, a Twitter app he eventually sold to Twitter. Apparently he patented the idea sometime before the sale, so Twitter now owns the patent.
Update: A reader pointed out that this is not a patent...it's a patent application that hasn't even been reviewed yet. But it's clearly a novel invention and most likely will be accepted when reviewed. (thx, mike)