Gmail has introduced a new feature allowing users to send free SMS messages through its integrated Chat. To activate the feature, visit the Gmail Labs page and scroll down until you see the appropriate listing. To send a message, just type a phone number into the search box at the top of the chat window on the left side of the Gmail interface, and hit ‘Send SMS’. Numbers can be associated with contact names so you don’t have to keep manually entering them. Recipients of these messages can respond by simply hitting ‘reply’ on their cell phones to send their own SMS message (Gmail ties a unique phone number with each of your contacts).