Galco has a few: http://www.usgalco.com/HolsterG2.asp.
I picked up a Glock 21 "Short Frame" last week for HD. I'm wondering if there is a holster on the market this soon for it. I know the Blackhawk Serpa for the standard 21 won't work, because of the Picatinny rail. I'm wondering if this would be an issue with any leather holster?