Why not? Once someone implements a good-enough garbage collector that can be used by a multitude of garbage collected languages.
Java has a strange way of handling object lifetimes that complcates things, but it's not the norm.
Considering Rubinius uses LLVM that's not quite true, and further, just because people haven't succeeded in taking it all the way it doesn't mean you can't. Maybe it's just hard.
For example, if you're willing to sacrifice a few features that make compilation difficult you actually can compile Ruby: RubyMotion (http://www.rubymotion.com/tour/how-it-works/) does it.
The biggest problem is something like eval, but if you're willing to live without dynamic features like that you don't have a lot of impediments to compiling to LLVM.