Oh yes, again. Now the friendly and kind developers Google has added the ability to send SMS messages via the site of its webmail Gmail. Users of Google’s Gmail service can now send text message chats to mobile phones using the webapp’s built-in Chat feature.
You must activate the feature from the Labs section (you can recognize by their green icon at the top of the page.)
To activate the chat feature go to Settings –> Labs and activate text messaging in chat.
Once activated, you are headed to the area reserved for gtalk, and start typing a phone number into Chat’s search box and you’ll see the option to send an SMS.
You can send messages to your friends, who may identify as yours to come from a certain area code (406). They can then write directly to the Google Chat and start a conversation.Also, your friend can save that number in their phone as belonging to you, and they can even use it to initiate new chats with you.
UPDATE: Google has rolled back the SMS feature in Gmail due to a glitch. It will be available again in about 2 weeks. Check out the official word from Google Blog