Today Google announced that Video and Voice “chat” is coming to Google Talk on Android. I just got an Acer Iconia Android tablet yesterday, and it already supports this.
Understand what this means - you’ll be able to call and video chat with other Android phones, tables, and anything that can run GMail & GTalk in the browser. No need for a phone carrier. All that you need is network connectivity, which could come in the form of ubiquitous wifi.
Sure other apps are doing something similar. There’s Skype, Qik, Fring, etc., but I already use Google for my phone. Because of that I already have GTalk - built-in. All my contacts are already there. I think only Google can make this ubiquitous. Google Talk is based on an open protocol, so anyone can implement an app that integrates with this service. You also have Google backing the connectivity.
Also remember that not too long ago, Google tied Google Voice to GTalk so you can make phone calls from your PC. Free calls at that. It’s all coming together now.