Melbourne CBD Target was renovated a month or so ago. The new store is free cabinets where you can lock you mobile in a box and recharge you phone.
Previously Crown casino was the only other place i found that offered this service and they charged for it. Really good if you need some power to meet your friends.
From memory the Telstra store in Melbourne CBD (Bourke x Swanston) has this upstairs too. Right up towards the front of the store (furthermost from the escalators). You have to ask a staff member to help you put it in but once it's set up you can take it out yourself. BYO cable.