Not too many of the major manufacturers have been as free and easy with their source code as Sony have, in fact none of them have. Sony has continually contributed source code back to AOSP, showing that they understand the importance of this contribution to open source, and this speaks volumes about the company as a whole.
Sony has previously released AOSP builds for the Xperia Z and the Xperia Tablet Z and has just released the source for the Xperia Z Ultra, an absolute monster of a phone that (on size at least) compares with the Galaxy Mega and Note phones from Samsung.
Spec wise, the Xperia Z Ultra is an Xperia Z on steroids, the phone still carries Ingress protection making it dustproof as well as giving it limited waterproofing to a shallow depth, which may allow some of the more artistically inclined among you to do some underwater photography or perhaps something a bit more adrenaline charging.
For developers with a want to play, the open source files are available through Sony’s Developer Site and clocking in at 228mb.
Would you like to see more manufacturers contributing to AOSP? Who’s first on your list?