With the latest patch (and the one addition PyBuffer_Release() I noted
above), valgrind is happy wrt memory leaks.  The only problem valgrind
found is a read of uninitialized memory.  See
http://bugs.python.org/issue3657 .

I don't know the buffer code to know if this is the correct fix. 
However, it fixes the problems and that's probably good enough for now.
 If you can get someone familiar with the buffer code to review, that
would be great.  If not, this patch should be applied.