It's a one-size-fits-many socket wrench.

The metal pins are on springs which retract to conform around any size bolt head. Jim Gephart and Pat Haughton guessed correctly. Allen came close, recognizing how the pins behaved, and guessing that it was designed to remove stripped nuts. It would probably work very well for this, too.
EDIT: Gary Winters wins the "technically correct" award for his guess.