I was going to post from my PSP for novelty purposes but well, no way I'm wasting that much time.
I'm unsure as to the legality of providing something that helps people run ISOs and the like, so I'm not linking to it, but I guess there's a program called Dev Hook that allows you to run the 2.71 firmware and 1.5 Firmware at the exact same time. I've been playing with it and it's awesome. The package I got was predone so I just extracted it to the root directory on my memory stick, and ran it from the game->Memory Card menu like you do any 1.5 program. It launched the 2.71 firmware and I was able to use the webbrowser and play with the other new features. After turning my PSP fully off (hold the power button for 3 seconds), boom, back to 1.5.
Finally, I can start buying PSP games again. Heh.
"The world is populated in the main by people who should not exist." - George Bernard Shaw