Some hacker is working on a PS1 emulator for PSP. It's an Alpha version right now and can only run a simple demo but sounds promising:

http://pspupdates.qj.net/2006/01/psp....html#comments

As much as I'd love to see a PS1 emulator for PSP, I have a hard time believing that it can be done (at least one that's playable). What do you guys think? Is it possible or is the PSP not powerful enough to handle PS1 emulation?