The Gen 4 Glock 37 should be ready for sale in September according to industry sources. The model 37 is the latest in the Glock line to receive the Gen 4 treatment that includes, among other things, and adjustable size grip. Other Gen 4 Glock pistols already for sale or announced are the 17, 19, 22, 23, and 31.
The model 37 is chambered in .45 GAP, and has already been shipped to the troopers of the Florida Highway Patrol. In January, at the 2010 SHOT Show, Randy Pitts, a Glock district manager, described the FHP pistols to me. At that time, FHP was the only agency receiving the pistol and Pitts was unsure if the Gen 4 Glock 37 would be released to the public.
A full article on the Gen 4 Glock 37 sold to the Florida Highway Patrol is at the BlueSheepdog.com.