I really, really hope OS X does not eventually get bitten badly by
moving that fast, neglecting thorough bug-fixing and refinement of the
existing features on its way.
So yes, I do understand the huge challenges the Xcode team is facing.
The reality is that releases are slowing down. They used to be almost
yearly and they're now approaching 1.5-2 years between releases.
Interestingly, Windows folks have complain that it's taken 5+ years to
get Vista out the door. So the OS guys lose if they're too fast and if
they're too slow.