Is AppleTV the only device that can receive AirPlay VIDEO?
Didn't intend to answer my own question, but I found this March 2011 Bloomberg article:


  Apple Inc. (AAPL) is weighing an
  expansion of its AirPlay audio service
  to include streaming video from an
  iPhone or iPad to television sets,
  according to two people familiar with
  the project.
  
  Under the plan, Apple would license
  its AirPlay software to
  consumer-electronics makers that could
  use it in devices for streaming
  movies, TV shows and other video
  content, said the people, who asked to
  remain anonymous because the plans
  haven’t been made public. Apple now
  only licenses AirPlay for streaming
  audio. Devices that could be used for
  video may be available this year, one
  of the people said.


So apparently the answer is "not yet, but maybe in the future."