I tested this today with Ubuntu 11.10 and it worked fine. The workaround with openSUSE is not to use kerberized mounts. Mounting conventionally:
mount -t nfs4 server:/server.folder /client.folder
On Ubuntu you can go the whole hog:
mount -t nfs4 server:/server.folder /client.folder -o sec=krb5
Don't forget (unlike me who tried for 2 hours trying to access the mount as a local user) that the user wanting to access the nfs'd files has to either have logged in or have kinit'd to get a ticket before trying to go to the mount. Duh!
Updated Samba 4 post here
Updated Ubuntu post here
This is what it looks like on Ubuntu 11.10, KDC, NFS4 and client all on one box!
|Clockwise, Samba 4 KDC, nslcd and mount, me, rpc.idmapd and rpc.gssd|
|All systems go. Kerberos with everything.|
|rpc.idmapd at work. Perfect uid:gid mappings. (this is the bit that's broken on openSUSE)|