An exciting feature for Gmail was announced today, but it turned out to be a false alarm for now. Google announced they will be adding SMS capability to Gmail so you can text people from right from there. Additionally, getting a response from the person is just as simple.
When a someone receives a text message from you (that you sent from Gmail), replies are simply delivered to your Gmail account -- this makes it very easy to communicate with people that are offline, but through a familiar interface.
How does this work? Well, when you send a message to someone, it will be sent from one of 1000 phone numbers Google has reserved for this purpose. Gmail will then reserve that phone number for you to communicate with that single person. Each person you contact will be assigned a different phone number from the pool. This works because any one person will probably never need to contact 1000 different people like this.
Once it's officially launched, the SMS feature will be available in Gmail labs -- just like most of the new features they have added recently -- including adding your Google calendar to your Gmail account. Just click on the labs icon beside the "settings" link, and go from there.