I wonder what language/API it uses? Java or C++ are probably safe guesses.
C/C++ would be seem like a good guess (and my personal preference), but on the other hand it might allow lower-level access than they are prepared to give.
In reality, anything that compiles on Linux on the ARM processor could be game- python, ruby, c/c++, perl... but, that kind of access is probably just a pipe dream.
What do you think J2ME runs on?