As far as I can tell, Android has always been proprietary except for the parts they were required to release under the GPL (like the kernel). Their GUI libraries were closed source (at least when I was tinkering with Android), and clauses like this have been in their terms for a long time. Sure, they look more open than Apple, but Android is a long way from being as open as the desktop Linux distros and BSD systems.
Not correct. AOSP source code has always included full source for android.view., android.widget., and so forth. Which are, by the way, Apache-licensed, not GPL. If you'd like to look for yourself, it's here:
In recent releases (4.x, a/k/a ICS and later), some of the low-level GPU drivers are included as binary blobs, but the GUI libraries built on top of them remain, at the very least, source-available.
Parts of the graphics/GUI stack are closed source, mostly the lower level parts like the OpenGL implementations. Also codecs, camera sw etc are closed source.
