App for gmail video chat I just bought HTC incredible S. It has front camera.
How can begin gmail video chat?
The service is not available yet for Android devices:


  Voice and video in Gmail only works with the newer version of Gmail in supported browsers: FF 2.0+, IE 6.0+, Safari 3.0+, and Google Chrome.


However, it's likely they have something in the works. In the meantime, there are alternative services like Fring and QiK.