If the chess program is to be of any quality at all (I mean able to even play a coherent opening) you would need equipment that the iPod does not have. I honestly do not see an iPod (at least the Nano and Classic models) being capable of playing a game beyond randomly picking a move. Even the weakest players would find the engine easily beatable.
Chess involves having intelligent opposition, something those other games you mentioned do not involve.
The "intelligent opposition" in a chess program is checking a database of possible moves to counter yours. The ipod could easily handle that.
There have been excellent chess applications since the days of the Apple 2, and electronic standalone sets since the 70's. A typical ipod has about a 90mhz processor and 32mb ram, which is better than most computers fifteen years ago. It could certainly run a very competent chess program.