Fix verified in lvm2-cluster-2.02.56-7.el5_5.3.
With GFS mounted, I was able to reboot without issue:
Unmounting GFS filesystems: [ OK ]
Stopping HAL daemon: [ OK ]
Deactivating VG grant: 0 logical volume(s) in volume group "grant" now active
[ OK ]
Stopping clvm:[ OK ]
Stopping cluster:
Stopping fencing... done
Stopping cman...
dlm: closing connection to node 2 done
Stopping ccsd...
dlm: closing connection to node 3
dlm: closing connection to node 1 done
Unmounting configfs... done
[ OK ]
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.
http://rhn.redhat.com/errata/RHBA-2010-0432.html