Gmail seems to be on a roll with all the new features it has been introducing. Canned messages, Gmail for mobile, emoticons in emails and now a new feature that lets you send free SMS.

This new feature has been added to Gmail Labs that allows us to send and receive text messages and have conversations all from within Google Talk in Gmail.

Like all other Gmail Labs features, you will also have to enable this from Settings > Labs. Once enabled, you can start SMS chats by typing in a phone number in the Gmail chat box (left).

Currently, this feature is only available in the United States, and will soon be available for other countries too. Replying to your messages will cost your friends money, so try not to have useless conversations :P

This lab feature was previously added back in October, but was later removed because Google found some problem which did not let the Lab feature to fully activate. It was expected that it will be fixed in two weeks, but took two months instead.