TMK followed up his port of MAME, has ported the v0.96 version, and it's now called PSP MAME v0.96! This release has 6 editions as follows: NAMCO, SEGA, TECMO, CAPCOM, IREM and FAVO... and it also includes frameskip, a 333mhz option, and various screen modes.

The files go in PSP\GAME\MAMEPSP, and you put the games in \PSP\GAME\MAMEPSP\ROMS.