Percival has released the second Homebrew game for the V2.5/v2.01/v2.6 PSP Firmwares and this release is a Pong Game, heres what he said:
"I have written a Pong game with Fanjita's Devkit for GTA homebrew.
Hope you guys like it!
Note: I have no idea how to let GTA load another file besides tetris.bin, so the Pong game file is called tetris.bin. Please don't be confused.
Note2: Only tested with 2.01 and EU GTA"