From Gambit wiki
Want to learn more about lisp/scheme and for Gambit Scheme come from iPad/iphone, before use Palm. I have some exposure to scheme as I have tried to go through SICP (via books and online video/script from MIT open course), even though not working all the exercise. Just a hobbyist really.
So far I evaluate a few Scheme (no Lisp) under iPhone and iPad. Gambit scheme seems most promising.
Let us see how it goes.