Corrected entry: Merry and Pippin drink Ent draughts in TTT and grow taller. At the end of ROTK when all the hobbits are standing together (Aragorn's crowning in Minas Tirith) Merry and Pippin are no taller than they were to start with (compare with the group shot at the Council of Elrond in FOTR as one example). Yes, Merry does say "everything's back to normal", but that's because they've had equal amounts of the draught so he's back to being the tallest. The book states the effect is the draught is permanent, and the film doesn't suggest otherwise.
Bob Blumenfeld
26th Dec 2003
Correction: I think they are, and are intended to be, taller than before, but not noticeably. The book implies they became considerably taller, but the movie specifically indicates only two inches. In the last scene, when Frodo is saying his final farewells, he is slightly shorter than either Merry or Pippin.
Bob Blumenfeld ★