Downgraders allow people who regret having upgraded their PSP firmware to take a step back in time. Previous downgraders only worked up to 2.5 firmware, but today's downgrader will work with PSPs, firmware 2.71. This program takes advantage of the libtiff exploit uncovered a few days ago and is provided by Dark_Alex, with the help of Mathieulh. As long as you follow the directions, your system shouldn't be bricked, but as is the case with any program that alters crucial system software, you should run the program AT YOUR OWN RISK. It's not going to be easy, but if you're determined, this is the key.

See the development website to get the file. Before you begin, make sure you do not have a TA-082 PSP. Check the picture to the right to see how to identify your system. If you see that text in your UMD reader, you're out of luck... for now (the homebrew community is hard at work for you too!).

[Update 1: Links to the original source of the downgrader. You gotta give credit where it's due! Thanks, DCEmu!]
[Update 2: QJ reader Mr. Dank has provided a video of the process. Watch after the cut.]
[Update 3: Just visit this page to see a really easy way of using this software.]