Essentially, this application (which I call "RemoteUnlock") bypasses the actual "unlocking" code in the winlogon process and simply switches the visible desktop back to Default. An interesting side-effect of this is that Windows (specifically winlogon) still thinks the computer is locked. You can see this when you run RemoteUnlock because while the computer is "unlocked", hitting Ctrl-Alt-Delete does nothing. Why? Because, Ctrl-Alt-Delete is handled by the winlogon process and, as far as it's concerned, the system is still locked. Since a locked computer should already be showing the Winlogon desktop, the system (incorrectly) sees no need to activate the Winlogon desktop again.
For this reason, RemoteUnlock will "re-lock" the workstation upon termination. (More specifically, it will switch back to the Default desktop.) Otherwise, the system would be in some weird limbo-state where Ctrl-Alt-Delete doesn't work as expected.