Google has been offering video chat through Gmail for a few years now, however they are currently testing a new ability for higher definition video chat than was offered before.
If you are curious and wish to test out the new service, go to the Settings tab, then Gmail Labs, then turn on "Video chat enhancements." When the option is selected, the video is crisper and the video window itself is larger, the Gmail blog reports.
The new Gmail Labs video service works using a "new playback mechanism which enables widescreen VGA and frees up valuable
resources on your computer." Using this new technology will help allow this service to be used on all types of devices, including netbooks which traditionally do not possess the ability to use typically CPU-hungry services.
Do note that for this Lab to work, both users must have the feature turned on. If you get to the point where you wish to stop using the new service, you can simply revert to the older video chat by disabling the lab.
Google also mentions that by turning on this one video enhancement lab, it will automatically enroll you in the other video enhancement features as they are rolled out by Google into testing for the lab. What these new labs are, the company would not specify, however they did say more were coming soon.