PSP IR Frotz is "a PSP port of dumb Frotz." What they really mean to say is that enables homebrew for some good old adventure games.
Alright, time for the serious stuff. PSP IR Frotz will enable you to play some good old Infocom games on your PSP. More importantly, instead of using other methods of input, it'll work on Palm and Targus IR wireless keyboards.
Notes for this version: According to them, PSP IR Frotz will probably only work with games meant for the app it ported. That being said, you can probably only play up to Z5-type games, as that's the limit of support for the original Frotz app.
In any case, give it a try. We'll leave it up to you to find the necessary files to play the actual games though. Enjoy!
Notes for this version: The difference between this PSPAtari v1.0.7.irkb and the other PSP v1.0.7 is the .irkb: thanks to KangKengKingKong's efforts, Zx-81's Atari emulator will not work with Targus or Palm IR wireless keyboards. Related artile at QJ.net explains the basics, while the README_IR shows you how to plug this baby into your PSP.