The head of Google's Android Open Source Project (AOSP), Jean-Baptiste Queru, made an interesting proposal recently. He added a new device to the AOSP repository, but this is no Nexus variant. Queru created an empty git project for the Sony Xperia S, but he needs the community to get behind the initiative. This will be the first device not designed under Google's supervision to be supported under AOSP, and that could be a big deal.
AOSP has been getting more robust as time drags on. Back in the pre-Froyo days there was only a little usable code posted for hardware targets, but more recent Android releases have included exact source files.