It may be a mistake or it may not, but you can currently grab Fable III for the grand price of £0.00.
Using this link you'll see that the full game is listed with a price, however if you click purchase and then select the option to 'use Microsoft Points' you'll grab it for free.
Could this be the 'Special Surprise' that Microsoft has in store for Xbox 360 users tonight? Is it planning to replicate Sony and give away a free game a month perhaps or something along those lines? Or is this simply a mistake?
Either way, grab it now.