JamVM is a new Java Virtual Machine which conforms to the JVM specification ^[1] version 2 (blue book). In comparison to most other VM's (free and commercial) it is extremely small, with a stripped executable on PowerPC of only ~200K, and Intel 180K. However, unlike other small VMs (e.g. KVM) it is designed to support the full specification, and includes support for object finalisation, Soft/Weak/Phantom References, class-unloading, the Java Native Interface (JNI) and the Reflection API.JamVM currently only includes an interpreter (keeps it small). However, the interpreter is highly optimised, and performance is on par with a simple JIT. As most of the code is written in C it is easy to port to new architectures.

So far, JamVM supports and has been tested on the following OS/architecture: Linux (PowerPC, i386, ARM, AMD64, MIPS) and MAC OS X / Darwin (PowerPC, PowerPC64, i386, ARM). The last one is built using unofficial toolchain and tested on a jailbroken IPhone.

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The last version is 1.5.1 is released on 10th of March 2008. Here is a link ^[3] to sourceforge project.

You can get more info about java here ^[1].