Java FX Mobile was launched today. Although there is lots of media coverage, very few news sites say exactly what it is.
Digging deeper, you might like to look at the article "Three Reasons Why Your Next Java ME Mobile Application Should Include JavaFX Mobile" and the official Java FX overview.
Java FX seems to be a UI layer that can sit on top of multiple JVMs. The ‘mobile’ part is the fact that it can sit on top of a Java ME JVM. The UI layer is a declarative syntax file that describes the UI and can cause calls into Java ME.
The main advantage of Java FX as I see it is that you can have one screen definition (or similar screen definitions) for different platforms. So you might, for example, have the same or similar UI for desktop, phone, navigation device, settop box or whatever.
Maybe I have missed something but these types of device usually need different UIs due to differing screen attributes. Each has to be optimised to show the data in the best way given the screen orientation, shape and size.
Until someone can convince me otherwise, I think Sun’s LWUIT probably offers more for mobile developers.