is it desirable to restart gnome on squeeze2wheezy upgrades, like it was for
I'm not sure it is desirable, the GNOME team should speak up about this.
On the other hand: currently the Release Notes say that the a system reboot should be done after the a new kernel is installed. For some systems this would be done after a minimal upgrade (i.e. running 'apt-get upgrade' but not 'dist-upgrade') and for others this would happen after the dist-upgrade, this depends on what the sysadmin prefers.
Maybe we could just say in the Release Notes that a system reboot is recommended (in non-critical systems) right after the full system is completely upgraded to confirm that the system boots up properly, all the services start up as needed and no errors are presented in the boot process. This would cover both the GNOME case (if it is desirable) and others, but maybe it is too drastic.
Else, we should document this as requested by this bug. Patches welcome.
Please bear in mind that translators are actively working now in the Release Notes, if a patch is required, please send it as soon as possible so translators have time before the release to update their translations too.