Normal, non-op players can still use player selectors in /tell.

In 14w04a, Dinnerbone fixed the bug that allowed normal players to use player selectors in the /me command. This however was not fixed for the /tell command. All player selectors can be used in /tell. Using this, it is possible with some simple math to locate a player's exact location on the map (trilateration) using selectors such as @p[name=???,r=???].