Tamarin (Again)

Artima has another post about Adobe donating its Tamarin virtual machine to the Mozilla Foundation, which references this post by John Resig. Long and short, it means that languages other than Javascript may be able to run within the browser (well, a browser), though the stack will be rather complex: IronPython/IronRuby rely on the Dynamic Language Runtime (DLR), which will ship with the Common Language Runtime (CLR), which will be mapped by IronMonkey to ActionScript Byte Code (ABC), which will run on Tamarin. What makes this really interesting is Resig's follow-up article, which discusses "why Tamarin rather than Mono or the JVM"?