Recently I tried to get animations to work for the Mac OS X backend with the new timer framework by implementing a TimerMac class that inherits from backend_bases.TimerBase. This seems to work fine; the code is uploaded to SVN if you'd like to try it.
I am not sure what to do about blitting though. I can imagine two uses for blitting: Either to make sure that the next figure appears instantaneously as a whole after it has been drawn off-screen, or to precalculate a background figure that is used repeatedly, and upon which the changing parts of the figure are drawn.
The latter would make sense for the Mac OS X backend also, but the former would not. Effectively, because of double buffering in Quartz all figures are automatically blitted already.
So my question is: What is the purpose of blitting for animations in matplotlib?