Google announced today the impending release of Google Talk for Android that supports video calls over 3G, 4G and WiFi. The updated version of GTalk will hit Nexus S devices in the next few weeks and other Android 2.3+ devices after that. Video calls will be possible on the Nexus S after the update, but there aren't many other devices running Android 2.3+ other than Honeycomb tablets, which will get the update "in the future."
Video calls can be made between users of supported Android devices and desktop Google Talk users. Simultaneous video and text chats are possible, with video pausing automatically should the user switch to another window. The audio stream will continue playing when the video is paused, a nice touch.
It's nice to see Google getting Talk updated to support the front-facing cameras that are now common on most Android phones. It is too bad that not many phones are running a version of Android current enough to support the feature. It is a reason for prospective Android tablet buyers to pick one up, and another reason for Android phone owners to lament the lack of OS updates.