"The code is expected to be brought into the fold of the publicly available Android source code over the next few weeks."
Google is doing Open Source wrong.
By that, it was meant that the code would be merged from the separate Cupcake branch to the master branch. This was actually completed a few days ago -- ahead of the original schedule.
I have not been following it very closely, but I wonder how much of the reason there was a "private" branch was to give the perception of a stable, non-changing code-base, like nearly every other phone platform has at release, to get more people on board, but without locking up development in the meantime so that further progress couldn't happen. I can completely see a reason for doing this that is social/political considering the history behind handset development and release.