It figures that in the strange world of Sony, a downgrade to previous software would be an improvement. That's the case with the PlayStation Portable (PSP), where hackers have released a firmware downgrader that turns a 2.6 or 2.5 version of the PSP into the more hackable and homebrew-friendly version 1.5.
Our beloved Kotaku nerd brothers warn you about fooling around with this firmware update (downdate?), though, because if you don't follow the instructions to the letter, your PSP might become an expensive, shiny, black doorstop.
Roll Back Your PSP To Its 1.5 Glory [Kotaku]