That's a "classic", we usually review our plans for GNOME for the next cycle.
That's going to be a controversial topic but I want to suggest we stay on stable GNOME this cycle, the reasons are (in random order):
tracking unstable GNOME is taking lot of resources that we don't invest in our desktop (packaging a new stack every 3 weeks, dealing with transitions, regressions, etc)
our desktop is quite less "stock GNOME" than it used to be, which means we have extra integration work to do and it's less trivial to do those "on the way" during the cycle
GNOME unstable series and Ubuntu "working every day" are hard to conciliate goals
GNOME is not communicating early enough on what is coming for us to discuss next cycle at UDS (see nautilus 3.6 in quantal)
GNOME is shipping stables with transitions half done (see gstreamer 1.0 this cycle) which is not something we want in Ubuntu
our "feedback loop" with GNOME is not really working nowadays, they don't have time to look at most bugs and we hit regressions and sit on them until somebody on our side has time to look at them, which means neither GNOME or us benefits much from tracking unstable GNOME...
On the con side though:
it gives us less opportunity to work with upstream on resolving issues
we don't get early feedback on what is happening
the new version of libraries might have APIs our app writers might want to use