New patch:
 - limit memory footprint: use a static buffer to store the frames, 
with a maximum of MAXDEPTH frames (default: MAXDEPTH=100)
 - if there are more than MAXDEPTH frames, jump to the frame MAXDEPTH 
on error (it's like a truncated traceback)
 - don't call segfault_exit() in PyEval_EvalFrameEx() if 
segfault_enter() was not called

On Ubuntu Gutsy, for MAXDEPTH=100 the memory footprint is 19996 bytes. 
I think that it's small, but it's possible to reduce the footprint by 
using less frames or disable the alternative stack (needed for stack 
overflow errors).