I ran across this puzzle in the SNES game Lufia II, but
it has been around since
before that. In Lufia II, it is called "the world's most difficult
trick" and this name is not uncalled for - it is a fairly difficult puzzle.
However, the state space is small enough that a computer can easily find the
minimum solution by brute force, so I wrote a program to do just that. Below
is its solution, requiring only 116 steps.
The object of the puzzle is to slide the blocks around in order to move the
large square to the bottom center (so that your character can reach the items
on it, at least in the game).