Pandora's battery unbricks all PSP systems
It appears that the Prometheus project has the top names in the PSP scene: Adrahil, Booster, Cswindle, Dark_AleX, Ditlew, Fanjita, Joek2100, Jim, Mathieulh, Nem, Psp250, Skylark, TyRaNiD. The release of Pandora's battery was supposed to come later, around the time of PSP-2000's launch. However, it appeared that the program was leaked early, and being sold for profit, something that irked the team greatly. "In order to prevent small fortunes being made by leeches, we are giving this unbricker away for free."
Make sure to follow the instructions included with the package carefully. Once you successfully run this unbricker, you'll have a PSP with firmware 1.50 which is ideal for homebrew.
[Thanks to everyone that sent this in!]