I think the dollar coin is a bad solution to the problem of paper dollars wearing out quicker than coins. A better solution would be a RFID device (like Speed Pass) that a person loads up with $50 or whatever amount he/she chooses, and then just wave it over the vending machine, stamp machine, or cash register, etc. The technology for this is rather mature by now. Some cards already have a chip inside. American Express Blue? Keys could be encrypted to 256bit which should be safe enough for a $50 and under type of "petty cash" system.
This is if they are unwilling to make quarters into dollars and dimes into quarters and nickels into dimes.............
