Skype today released a version of their VoIP application for Google Android. As with other versions, it is completely free and provides free Skype-to-Skype calls and IMs, both one-to-one or with a group. You can also make regular calls (billed at Skype’s rates) over 3G and Wi-Fi over 3G and Wi-Fi.
There are a couple of limitations unfortunately. Calls in the US are only possible over Wi-Fi. There are also some issues on the Samsung Galaxy S that are currently under investigation by Skype.
Skype for Android requires Android OS 2.1 or later. It’s a free download available from either the Android Market or directly from skype.com/m from your phone.