Those Googlers are still up to all kinds of geeky crazyness. The good folks of Mountain View have just added a new feature to Gmail—the undo for e-mail.
Once enabled in Gmail Labs (that’s under the Settings menu in Gmail), Google will add on a five second delay to all e-mails that you send. You’ll have five seconds to click undo at the top of your message if you decide you want to retract it. If you don’t, it will be sent as usual. Simple as that.