A glorious trend for Java in embeded applications is foreseen by the Java evangelists. We are again where someone is out to "prove" that a given language is the best for EVERYTHING. Many embedded applications are made in millions of units (currently working on a 20M+ unit) and a penny is real money. Here to spend the hardware (memory) to support the Java overhead would be ridiculous, although I'm sure some management type will pick up on the buzzword and try to have it done. With the cost of hardware continuing the downward trend, I have no doubt that some embedded Java applications will come up although I doubt we will see many in the '51 world. If you can afford the hardware to use Java your unit count will probably be such that you are more concerned with development cost.
Have fun,
Erik