Apple Directory / Profile Manager  - Restricting simultaneous same user logins on multiple  machines? We are using Apple Directory for internal user authentication. We want to restrict a user to login from a single machine at any one time. I have been trying to find a way to do this in Apple Directory without any luck.

Is there a way to do something similar in Snow Leopard or Lion server?
I assume you mean Open Directory, not Apple Directory.

There is a check box in Workgroup Manager in the user's account.  Set it to not allow simultaneous logins.  This box is present in WGM on 10.3 - 10.6  I know that Lion deals with workgroups a little differently.