IKVM.NET is a Free Software compiler which can compile Java bytecode into .NET bytecode, and execute Java bytecode directly using the system's .NET runtime (whether Microsoft.NET or Mono). It's based on OpenJDK's source.
Originally Posted by mateli
directhex@dream:/tmp$ ikvm hello
directhex@dream:/tmp$ java hello
directhex@dream:/tmp$ ikvmc -target:exe hello.class
Note IKVMC0001: found main method in class "hello"
Note IKVMC0002: output file is "hello.exe"
directhex@dream:/tmp$ mono hello.exe