I've (finally) made my own 'custom firmware' based on Dark_AleX's original proof-of-concept.
BEHOLD:
the Puzzle Bobble Custom Firmware!
(You can get that video with some Mr. Roboto hotness, too.)
Features:
* Puzzle Bobble Pocket, right on flash0. Built in. No need for a UMD or memory stick!
* Sleek, sexy PSP XMB interface!
* Whopping 64KB of free flash0 space!
* Recovery booter - load your favorite recovery app to get back to a useful firmware!
* Still runs homebrew (in kxploit format) and 1.50-compatible UMDs! Wowie zowie!
Lacks:
* XMB music plugin :/
* XMB video plugin :/
* Japanese... anything :/
I do plan to release it, but it'll be in the form of an installer that rips files from YOUR ISO DUMP and YOUR FIRMWARE DUMP. It will NOT include all the files you need.