I upgraded a RH 6.2 box to Pinstripe. When I started X, GNOME failed because it was configured to use Sawfish, but Sawfish had not been installed. To install Sawfish, I had to simultaneously install several libraries: librep, librep-gtk, and librep-gtk-gnome, as I recall.
We have officially moved to sawfish as the default window manager. This problem is fixed in the latest versions - it checks to see what you are running (If you still have the old E we give you the option to update to sawfish or run E standalone) should not be a problem anymore