We don't see it in our Gmail settings (yet), but Webmonkey reports that Gmail Labs has added a feature for sending text / SMS messages using the built-in Chat functionality. Turning the option on in your Gmail account settings apparently enables you to send an SMS as soon as you start typing a phone number into Chat’s search box. We haven't been able to try this out ourselves yet, but Google lists text messaging on its ' What's new ' page (only for US phones, it seems).