The first feature is similar to a live chat box that you can add to any web page and chat with anyone via your Google Talk or Gmail account. Google calls the feature “chatback,” and it allows anyone, even without a Google Talk account, to talk to you via your Google Talk account.
The second feature is “invisible” mode for your Gmail and Google Talk status. Google says this feature comes in handy when your away status is just not good enough. This way people don’t even see you to instant message you.
The Google Chatback is very easy to add to your page. All you need is a Google Talk Account and then you go to this page and copy and paste the code where you want the chatback badge to appear on your page. Then your web site visitors can chat with you via the chatback feature.
The invisible mode feature is available in the new Gmail code features.
One new thing that people have been also noticing is that by default, many Gmail accounts have two emails. By default they have an @gmail.com but they also have an @googlemail.com.