How can I allow users to see who is locking files on the server?

I think you are referring to a file being locked by being opened by another user. Depending on the application, file locking may prevent other users from opening the file or simply force additional users to open the file in a read-only mode.

It is possible for administrators to use the Computer Management's Shared Folders tool to see what shares are currently in use, what files are currently in use and which users are currently using the objects. But I don't see an indication of whether the files are locked, how they are locked or what application is doing the locking.

It is possible to grant users access to view this information by creating a custom MMC console with the Shared Folders snap-in. The console can be pre-configured to view only a single system or allow the user to change system context. Be sure to set the console to user mode before distributing to non-administrative users.