Google's new Android SDK is a lot more than a Linux distribution, its a complete and documented application framework with developer tools support. The primary language for application development is Java, with a special runtime called the Dalvik virtual machine that is designed to run efficiently on a battery powered device.
The SDK is 55MB, there is available Eclipse support.
Sample applications include Google Maps, mail, webkit based browser and the usual Phone and PIM stuff. The user interface seems to be based on a new set of Java classes, but there is also direct access to the display in C/C++ using SGL for 2D and OpenGL ES for 3D, and audio and video players for things like mp3 and H.264.
From a first pass through the docs, a lot of work has gone into this already. It looks as if it should be portable
to a homebrew phone without much difficulty, and from then on, we are likely to be leveraging a much larger community than the other open alternatives. It appears that the current state of the OpenMoko project is that they have made some progress and have a somewhat usable toolkit written in Python, but that C/C++ development based on GTK+ is painful, and documentation is scarce. It looks to me as if Android has taken the same basic inspiration as OpenMoko, but with a much more professional execution, and with a Java based developer platform.
We will be discussing this at the Homebrew Mobile Phone club meeting on Wednesday. We are holding the meeting at Mozilla's offices and will also be discussing their work on a mobile version of the Mozilla browser.