Ask HN: Comparing Virtual machines

What are the differences between virtual machines like JAVAs and Erlangs?

Is the future virtual machines?

There is a lot of work going into bringing dynamic languages to the JVM and Sun seem to support that strongly. There is also some efforts to bring other languages to the Erlang VM.

Is it correct that VMs offer safety but have a slight penalty when it comes to performance? I understand the penalty for speed but a virtual machien offers another layer of abstraction, and it is software and software is less reliable than hardware in general right? So wouldn't that make it less safe? Or it is different types of safety?