Linux 3.3 Kernel Released With Merged Android Support
Google didn't just changed Java for Android, the Linux Kernel was modified also.
And those changes, while available as open source, didn't make their way back to Linux.
Now, mainstream Linux kernel did include Android changes...
Google has done similar with web browser, too,
where open source project WebKit is used as platform for open source project Chromium,
that is base for Google's web browser Chrome,
as well as a few other browsers...