It’s taken a while but Microsoft has finally realized that it’s futile to charge customers an extra $100 just so they can use a keyboard with their Surface tablets… for a limited time at least. CNET notes that Microsoft has started promoting a limited-time offer where users who buy a Surface starting on May 31st will get either the Touch Cover or the Type Cover click-in keyboard for free. We have no idea how long this offer will last but it wouldn’t surprise us to see it extended for a long period of time if it helps boost sales. As we said last year, Microsoft’s decision to charge an extra $100 for a keyboard was rather puzzling since the keyboard was billed as an essential part of the tablet and key differentiator from Apple’s iPad.