how to set breakpoint at exception throw?

["Scott McPeak" <smcpeak@cs.berkeley.edu>]

In the debugger, I'd like to put a breakpoint essentially in the
'raise' function.  The idea is to get control whenever an exception is
raised, and be able to take a backtrace.

Any ideas on how to do this?

Note: I'm mainly interested in exceptions thrown by the runtime
(e.g. stack overflow), not those thrown by my own code, so simply
wrapping every 'raise' is not enough.

-Scott