Leopard loses directory info manager
Luckily the other Mac users at NetApp are much more NFS savvy than I am; they helped me set up Tiger so that both my home and work account UIDs match those on my respective servers/NIS domains. Therefore, I can mount NFS shares in both locations and have equivalent permissions. With Leopard's autofs, this is unbelievably convenient!
At work, my Mac can access the whole huge NFS automount tree. At home, I can access my server. In both cases, the access appears to have paths within my local filesystem. This is so much better than CIFS, it is amazing.
Anyway, if you want to get/set the UID for your Leopard user, you want to use dscl. Try the dscl man page on the developer.apple.com site, it has examples in addition to the command documentation!