Off on semi-related tangent, is not the portability of Dalvik binaries largely irrelevant due to the extremely narrow range of architectures (officially only ARM) that Android is running on? Certainly you have variations between ARMv6 and ARMv7, but that's so trivial as to be easily automated with the click of a button. I could always take the Free Software bent and note that VM-based software is irrelevant if you have the source code.