As of Thursday, April 2's maintenance window, PASS Samba Gateway now supports multi-author editing from Microsoft Office 2007.
The problem was rather a complex one to solve. The symptoms were only present for Office 2007 and not other applications or previous versions, not present on all machines (some appeared to be "immune" for reasons still unknown), and only appeared for users who did not own the file; successful saves from Office actually delete and recreate the file, effectively changing the ownership. So individuals could create and re-edit their own files without problem. The problem also occurred only for GPFS filesystems and when CIFS oplocks (Opportunistic Locking - a client machine lock technique to implement file data caching) were enabled.
The problem symptom was that attempts to open a file in MS Office would seem to hang the application for about 30 seconds before an error message appeared:
"Access denied. Contact your administrator."
Between March 25 and April 2, each of the PASS CIFS Gateway servers were upgraded with GPFS client and Samba server updates, some of which had notable fixes for oplocks or Office 2007. Tests have shown this resolves problems seen by at least two separate units.