See this thread on the bug repository for wxWidgets on SourceForge: http://sourceforge.net/tracker/index.php?func=detail&aid=1396402&group_id=9863&atid=109863 The stack trace shows GSocket::Close calling a pure virtual function, crashing my application.
This turned out to be my bug. I had a wxWidgets object declared as a global, so it was being destructed AFTER wxGTK had shut down. My apologies. Please disregard.