The "can" branch is now published on github, currently it's in sync with the upstream "ide-1.5.x" branch.
I would like to thanks Palliser and aethaniel for the work done so far, and all the other that have contributed to this discussion.
https://github.com/arduino/Arduino/tree/can
https://github.com/arduino/Arduino/tree/can/hardware/arduino/sam/libraries/CAN
Who is interested in development must checkout the "can" branch since its likely to diverge while the CAN library gets developed and the API evolves.
The CAN library is still far from its final shape, a lot of work needs to be done, BTW its public now and I'm excited to see what the community can get out of it.
Finally: thanks you all for your patience, I know that more than two months of wait seems a lot but, believe me, time flies and sometime is very hard to keep up with the amount of inputs coming from this amazing community.