Hmm... I've been able to send SMS messages from Yahoo! Mail/Chat for more than a year now (both the website and stand-alone IM client). Even better, my Nokia cell-phone has a built-in Yahoo! Chat application that uses my SMS message alotment (over Yahoo! IM servers), meaning I don't need 3G or GSM to chat over IM.
GMail isn't going to be another Microsoft are they? Watching what others have already done, then getting praise for doing the same thing just cause they're Google (Chrome browser anyone)? Oh, and GMail has been out for what, 3-4 years now, I think it's time they rolled out of the Beta stage.