SMS Text Messaging with GMail

Per the Official Gmail Blog you can now send SMS messages direct from your Gmail window. Just click on Settings, and go to the Labs tab. Scroll down until you see "Text Messaging (SMS) in Chat" and select Enable and Save Changes.

SMS messaging is currently limited to U.S, mobile phone numbers, including those on roaming. But Google expects it to include international numbers in the near future.

Note that while it might be free for your to send SMS messages to your friends via Gmail, recipients might get charged if they incur fees, especially if they don't unlimited text message plans.