Where is the DayZ saved game file located?

Your DayZ character is stored server-side and is linked to your CD-Key. As long as you are playing with the same CD-key, you will have access to your character.

To expand on OrigamiRobot:

The DayZ 'team' has what's called a 'Hive.' Think of this as a central database where everyone's character data is stored.. that is, your coordinates, your inventory, stats, everything.

The only thing that is local to you is your ARMA profile. For example: Player Name/Skin/Squad data.

You'll notice if you ever have joined a 'private' server that you have to start on the bean coast, this is because each private server has it's own local 'hive.'

Your dayz hive data is based on your CD-Key. If you were to buy Arma on a different steam account you could essentially have 2 DayZ characters.