I wanted to copy some files from my PC to my Mac. When I went to turn on SMB sharing, I came across this:
I was wondering about the identity of this phantom user. It turns out that it is the macports user. He doesn't show up on the login screen. He never showed up under 10.6. Apparently, Apple changed something about the way users are reported to applications.
If it bothers you, you can fix it with dscl.
sudo dscl . -create /Users/macports RealName macports
The first parameter is the machine you want to administer; . is apparently a shortcut for localhost. Then we give the command - we want to create a new key. Then we specify where this key should be created - in this case, the macports user's Directory Services path. Next is the name of the key - RealName is what appears to be used by the sharing dialog. (RealName is also assigned on users you create through System Preferences). Finally, we provide a value for this user's name. Now, we have this: