Both the 32bit and 64bit versions of gtk2 use the same configuration files for pixbuf loaders and IM module libraries. Things go wrong with 32bit apps try to load 64bit libraries (and the reverse). So, gtk2 needs the same treatment pango got -- arch-specific config files go in /etc/pango/$(HOST_TRIPLET)/
This is done in fc3. We don't plan to backport it to fc2.