I guess you can close this now.  Unfortunately SourceForge goes out of
its way to not make an easy link for the MinGW mailing list but you can
see the messages on 8th July 2008:
 
http://sourceforge.net/mailarchive/forum.php?forum_name=mingw-users&viewmonth=200807&viewday=8

Basically MinGW erroneously ships a .lib saying localtime is in
MSVCR90.DLL when it isn't.  That means there is no link failure but the
pyd will fail to load without information as to why.  Fixing the .lib
means that localtime is picked up from MSVCRT.DLL (ie no version in
name) and everything appears to work well.

The MinGW project also claims they only support MSVCRT.DLL and not any
of the numbered ones, so basically it is luck they work.  Noone pointed
out any compile time directives to direct versioning of MSVCRT.

I guess this is more fuel for the semi-regular flame war about free
software and free compilers on Windows, but not in this ticket!