YoYo Games has begun porting the Game Maker engine for the Mac, with plans to release a beta before the end of the year. Users will soon have the option to develop games on the Mac as well as run on the Mac.
This is carried out in parallel with work on writing the Game Maker runner in C++, which could eventually mean that games could possibly run on other devices such as the Nintendo DS.
Heh, you could also mention that the other amateur game creator, Multimedia Fusion 2, is getting Hardware Acceleration and an option to create Java executables thus making it available (to a point) for pretty much anything that can run Java :) - which I believe is quite a lot of things...
Of course it actually has to happen (ETA:Christmas) for this actually mean anything
Unfortunately it'll be another year or two at least before Multimedia Fusion is a good candidate for mobile games. They have incredibly strict limitations for memory and MMF applications squander resources.