Now you can run games which require 2.71 firmware
The Devhook 0.44 for Sony PSP has been released. It allows you to play games from your memory stick on your 1.5 firmware and supports games requiring up to 2.71 firmware.
After the release of v2.50 and v2.60 downgraders, this is some great news. Grab the latest Devhook from here. The page has full set of instructions as