Wireless Hotspot Creation?

ezodon asks: "I have been tasked by management to submit a plan on creating a wireless hot-spot in several of our locations. Management would like to be able to charge for the wireless access from our customers. Because of the desire to charge, I have not been able to find any Open Source software, and just a few commercial offerings. I have checked out PublicIP and LessNetworks wireless management software, but neither has a direct billing option. We already have a merchant account and credit card machines at all of our locations. Can anyone in Slashdot land give me some recommendations on how to get this done?"