To connect to an NFS export from a Mac OS X client, click the Network icon in the Finder to browse for your server.

Mac OS X Client can browse for NFS servers via the Bonjour protocol. To connect directly, choose Finder > Go > Connect to Server and enter an NFS server and path address, or press Command-K. Default settings dictate that the share point's icon mounts on the Finder's desktop. 

Excerpted from Mac OS X Server 10.4 Tiger: Visual QuickPro Guide