We are going to release several patches which are not included in official MySQL releases.
First one is automatically stack trace for x86_64 systems. Currently MySQL resolves stack in crash only for x86 boxes.
You can download patch for 5.0.22 source tree here.
How to use: place stack64.diff into main source dir; execute patch -p1 < stack64.diff. One important one: flag -fno-omit-frame-pointer must be added to CFLAGS and CXXFLAGS, by default GCC uses -fomit-frame-pointer on x86_64 systems (on x86 by default -fno-omit-frame-pointer).