The Glassfish server includes a Ruby and Rails implementation.

There's a Java Python that's well established.

The PHP implementation is not a Sun project. It's called Caucho, and it runs PHP quickly, compiling PHP to Java bytecodes.

There's no Perl-on-Java, and Perl6 is running on its own virtual machine.

There are Ruby and Python implementations for .NET.

It looks like there's a three-way battle of the managed environments. One is Microsoft with .NET. Two is Sun with the Java Virtual Machine, the first really big VM. Three is Perl's Parrot.

Somewhere out there are the JavaScript and ActionScript compilers.

Parrot's interesting because it's designed to run dynamic languages. Java and the MS CLR are designed to run static (typed) languages (that are object oriented).

The JVM is interesting because it's been around a long time and, like C before it, it has been ported to many platforms, some of them very small.