The developer of PPSSPP has come out and said he is going to port it to the App Store without JIT which will be interesting because its both the best emulator on Android and also an emulator of the best portable console.

I have Dolphin on my Xbox and it runs really well but I find 'home console' titles poorly structured for portable play. The PSP is brilliant for short bursts and I already have a ton of receipts from the PSN for all the games I would play so the roms, at least for me are not illegal :)