InvokeDynamic and other Java 7 features (method handles, NIO2) are definitely going to improve JRuby's situation, but maybe not in the way you expect. Indy and method handles will largely allow us to delete (or not load) code we currently generate to get the same effect. Smaller runtime, possibly a smaller distribution. NIO2 will give us more direct access to streams, process handling, and so on, so we can delete hacks we've written to do all that ourselves.

But perhaps the most interesting aspect of any new major Java release is that they're usually 10-20% faster across the board, due to new and better optimizations. As the saying goes, if your Java app isn't fast enough, upgrade to a newer JVM.

I think invokedynamic combined with more runtime profile-driven optimizations in JRuby could easily double JRuby's Ruby-execution performance (or better), and in many cases reduce memory churn too. Lots of good things coming...it's nice to have an army of VM engineers on your side.