I am using libstdc++ on MAC for developing extensions for firefox. I am getting crashes inside libstdc+ library when I am referring to it across multiple firefox extensions.
See the HOWTO at
http://www.cs.huji.ac.il/~etsman/Docs/gcc-3.4-base/libstdc++/html/17_intro/howto.html , specifically the section entitled
"The Standard C++ library and multithreading".