E-mail inception? That seems to be what Yahoo is aiming for here. Or perhaps simply a last ditch effort to drive up traffic inside its email service by tying it with other email services. To be fair, Yahoo actually added the ability to add other email accounts to Yahoo Mail last October, but it is only now that it is turning on that switch for Gmail, trying to sell the idea that using Gmail inside Yahoo Mail will be a win-win situation for users. If that even makes sense.