What are the differences with Khet 2.0?
From ThinkGeek:


  For those of you that loved the original Khet, you're gonna just flip
  for Khet 2.0, but we'll sum up game
  play for you who are new to the game.
  In Khet 2.0 Laser Game, there are four
  types of playing pieces, and two of
  them have mirrors. Game play is
  simple, and easy to learn, as there
  are only a few movement choices. The
  goal is to eliminate your opponent's
  Pharaoh. And, you eliminate the
  Pharaoh just like they did in olden
  times - by firing a red laser! And
  this is where Khet 2.0 kicks the game
  up a notch.
  
  In the original Khet, the lasers were
  part of the board. But in Khet 2.0,
  the lasers are built in to special
  Sphinx pieces that perch in the corner
  and can now rotate to change the angle
  of the beam (because of this change,
  the board is very slim and now built
  to travel)! Your laser is fired after
  your turn and bounces from mirrored
  piece to mirrored piece (always
  shooting off at a 90 degree angle). If
  the laser hits any piece on a
  non-reflective surface (with one
  exception we'll leave as a surprise),
  that piece is removed from play. If
  you eliminate your opponent's Pharaoh,
  you win. If you eliminate your own
  Pharaoh, you will be mocked for all
  time (because it is possible). Khet
  2.0 Laser Game is the next generation of the best laser game of all time.


So it seems that the form factor has changed, the lasers can be rotated, and there's a new piece added.