Following the installation of the OpenSolaris server, I've had some problems with the NFS mounts. I've created an export for a fileserver (datapool/filestore) and although I have setup identical UID/GID maps between my clients and servers, when I mounted the filesystem on my Linux server, I found that files created were owned by nobody:nobody.
At first I thought this was due to some configuration problem in the OpenSolaris installation, but after trying it with the Mac as well, I realised that the mapping was fine. This then pointed to the OpenSUSE 11.1 installation.
The problem turned out to be the Domain setting in /etc/idmapd.conf. The value in this file was different from the OpenSolaris NFS domain. Changing that and restarting the idmapd process (which I did by rebooting the server as I had a kernel update to do), fixed the problem and I now map correctly.
The next step is getting a Samba and Windows client to authenticate me correctly with the OpenSolaris CIFS server. That might be more difficult, but I'll update here when it's done...