Tim Bray : "I'm pretty sure anybody who's been to the mat with the Android APIs shares my unconcern. First of all, a high proportion of most apps is just lists of things to read and poke at; another high proportion of Android apps are decorated Google maps and camera views. I bet most of those will Just Work on pretty well any device out there. If you’re using elaborately graphical screens you could do that in such a way as to be broken by a different screen shape, but it seems to me that with just a little work you can keep that from happening."
Tim might want to live through a few real handset projects to understand portability costs. All that little work adds up and is sufficient to hurt the bottom line of a company or an individual, perhaps enough to keep them with Apple. Even if you could develop a portable .apk through disciplined coding, the verification testing alone will hurt, especially as the Android ecosystem of hardware and versions grows.
"Oh, and the executable file format is Dalvik bytecodes; independent of the underlying hardware."
I've heard the same said about J2ME bytecode.