From the WP-Hackers Mailing List:
In light of the big changes happening in the codebase and admin section,
we’re going to push back the next release to be aimed for early March.
This is the timeframe when 2.5 was originally schedule for, so we’re
treating the originally planned 2.4 in December as a skipped release, as
a result of both the holidays and the large changes which we weren’t
able to start on until late October.
There’s some good stuff in the oven, and we don’t want to rush it.
The new release shall be called 2.5. Various official docs and roadmaps
will be updated in due course.
So it sounds like we will need to wait longer for the new theme.