Skype was recently released for Android and available in the Market, a version which is no longer restricted to Verizon but which, as the description also states, does not allow calling using mobile data connection in the US.
DroidLife reports the application has been unlocked by an Android developer and in its unlocked shape it would allow users to place calls using their data connection on the mobile device. This might not be such a great news if you are using Skype on Verizon where the application is locked and bound to only work over their network but it your carrier’s color is different you might find it useful. Download the tweaked Skype application for Android allowing you to use data connection to place calls from here and install as you normally would. It does not require your device to be rooted.