Recently Gmail added New features like Smiley in Email, Google Calendar and Docs Gadgets in sidebar and Now they added a new Feature SMS. Now you cand send SMS from your Gmail Account embedded chat. The Official Gmail Blog hasn’t announced the new SMS chat feature yet but reports indicate that SMS support in Gmail Chat will be available for all US users some time today.

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When the service becomes available it will require you sign up for it through Google Labs. To do this simply go to Gmail, then Settings (upper right-hand corner of Web page) and select Labs. Simply scroll down and “enable” SMS chat.

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You are right that Google launched SMS on Gmail sidebar.But when I found this is not present yet.
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