http://www.lifehacker.com.au/tips/2008/10/31/gmail_labs_adds_text_messaging_to_gchat-2.html'Gmail's latest Labs experiment adds an option to send SMS text messages
to contacts from the Google Chat sidebar, at no cost and with replies
arriving as new chat lines. Like other Labs, you'll have to enable it
by heading to the Labs icon in your Gmail settings and enabling "Text
Messaging (SMS) in Chat," although the feature is apparently being
rolled out gradually to users. Once enabled, you can type and choose a
contact from the Chat sidebar and select "Send SMS" from the options
that pop up to the right of their name, or select "Video & more"
from the options dialog on a chat window. Enter a phone number, type
your chat, and Google tells the recipient that they can reply like any
other text. Gmail's definitely making a play to become your all-in-one
contact and messaging centre, and free text messaging is a powerful
tool to getting there.'