The features, which require a plugin [available for both PC and Mac OS X] allow you to initiate video and audio chats from within the web browser. You can even expand the size of the video chat, and thanks to the feature being based on a number of widely used standards, you should in theory be able to chat with a fairly large number of contacts who don’t need to be using the web interface [it’s also worth noting that one-way video and audio chat is also possible].
Unfortunately, the feature isn’t available just yet: the Googlers say the feature has only just begun rollout – however you can visit the Gmail videochat page to download the browser plugin and get ready for your account to be enabled in the next few days.
It’s been over two years since Google brought text-only Chat to the Gmail web interface: and whilst the feature has certainly seen a number of small additions in that time, I think it’s fairly safe to say that the efforts with Chat to date will pale into insignificance withGoogle’s announcement on the Gmail blogthat Video and Audio chat will shortly be arriving in an inbox near you.