See: http://bugzilla.gnome.org/show_bug.cgi?id=303649 for more details. We should get this in FC4, I reckon.
My understanding is that the savings are only VSS, not real physical memory so I like to understand what the real gain is before adding a patch that we need to carry around for the life time of FC4.
* Tue May 10 2005 Mark McLoughlin <markmc> 2.12.1-3 - Add patch to set the size of the IO thread stack to 256k in order to mitigate the apparent 10M jump in GNOME processes memory usage (#157297)