Skype Your Cellphone – Forbes.com
…the mobile phone does not need any special hardware and there is no need for a broadband connection or even a Wi- Fi connection. You simply download the iSkoot software from the iSkoot’s Web site. Then, when you want to chat over Skype, the call is routed over a regular mobile network which then connects to iSkoot’s servers. The servers bridge the call to Skype’s Internet network.
Note: I tried this just a few minutes ago and was extremely impressed with the ease of use and the quality of the call.