For any of you fortunate enough to own a 1D Mark III but unfortunate enough to be affected by the AF issue it seems that Canon has acknowledged the problem and is about to roll out a solution.
From Northlight Images
report of an alleged Canon letter to it's dealers:
... the problem can be linked to the adjustment of the AF Sub Mirror, and we believe that this affects only a minority of units in the market at this time
we are currently preparing a resolution for this issue ... ... Canon will accept these units for repair, but we will not be offering an exchange or return
As of today we are taking end-user inquiries with the above information through our Technical Help Desk on 08705 143 723 ...