The basic problem with running OCaml on Android is that pretty much everything (minus a few system services / daemons, for example) runs inside a Dalvik VM.  Everything that is a "real app" thus uses the facilities of the SDK to interact with the underlying system.  (Various services such as internet can be opened via a raw socket, and are protected via lower level system modifications.)

So while it's possible to write pieces of apps in OCaml, I don't think anyone's taken the time to generate wrappers around the Android SDK.  I was very skeptical that this could be done efficiently since you'd be jumping through JNI back and forth to bytecode / native code a lot, but I've talked to someone on the Haskell-cafe mailing list (I'll try to dig up the email) of someone who's said the penalty isn't as high as you'd think.

Kris