I recently set up a OpenSolaris based ZFS NAS for myself and use NFS to export a few zvols to my Macs.
Unfortunately the network volumes never show up in the finder when using the Mac OS X Directory Utility.app to automount them. I can access them just fine by opening the mount-point with the finder (shift-cmd-g) or in the finder.
The NFS exports are all fully functional, they just won’t show up anywhere in the Finder.
I should also mention that everything works as expected when I use the mount_nfs terminal command or use finder's cmd-k.