Using GPSim on an up-to-date Gentoo box I have come across another instance of a segfault from the GTK+extra library. The maintainer of both projects sent me the attached GTK+extra patch, which fixes it for me.
Created attachment 261320 [details, diff] Patch to fix crash with GTK+extra itementry I've tested this (briefly) in a local ebuild and it all looks good
+*gtk+extra-2.1.2-r1 (02 Feb 2011) + + 02 Feb 2011; Pacho Ramos <pacho@gentoo.org> +gtk+extra-2.1.2-r1.ebuild, + +files/gtk+extra-2.1.2-itementry-crash.patch: + Fix crashes with dev-embedded/gpsim (bug #353489 by Robert Pearce). +