What if you want Java on a jailbroken iPhone?

Then that's easy:

http://java4iphone.com/category/all-news/java/java-applications/

There's an example of using JamVM (http://jamvm.sourceforge.net/) on the iPhone, bridging the Objective-C classes with JocStrap (www.telesphoreo.org) and writing nice Java code like:

@Message
public Object preferencesTable$cellForRow$inGroup$
(UIPreferencesTable table, int row, int group) {
return cells[group][row];
}

...instead of:

- (id)preferencesTable:(id)preferencesTable cellForRow:(int)row inGroup:(int)group

While this works nicely, it's still cumbersome, and (obviously) not oficially supported.

Jost for the (few) of you who didn't know about it. Of course, good luck in trying to publish that on the AppStore.

Cheers,

Hugo