Ha ha! That's a good one.
First, J2ME != MIDP, although the widespread belief is otherwise. This is important, because technicaly, the answer is, it depends.
In MIDP, and probably in most CLDC profiles, JNI calls is not/will not be supported.
I think Personal
Java does support JNI calls. PersonalProfile, which will replace Personal Java will probably have the same support as before.
--Mark
hershey@vaultus.com