A J2SE JVM with JIT is blocking on GTK 2.10 support, which is earmarked for the N800 anyways --- literally as soon as GTK 2.10 becomes available, I'll have it ready.

J2ME is far more useful, at least to me, since it focuses on phone-centric apps. Small, lightweight, simple, and connected. GMail Mobile leaps to mind.

J2ME Polish is a good example, incidentally, of what can be done.

Given the "fun" of getting even basic PhoneME running, I'm happy to see actual Sun programmers dealing with it