Patches to add SPNEGO/Kerberos support for CIFS were recently committed upstream. I'd like to go ahead and enable this in Fedora rawhide now and target it for Fedora 9. It's still considered an experimental feature but it works well. Note that this also requires packaging the userspace cifs.spnego program to make it actually work.
Created attachment 289689 [details] config-generic patch to enable CIFS_UPCALL support