H.D. eventually sorted the problem out on the '09 model bikes, if i'm correct they are all now nitrogen filled and sealed. A temporary fix is to keep the inside of the gauge and the outside atmospheric conditions the same, this means drilling a small hole somewhere on the gauge. Another short term remedy is to try and get some silica gel into the gauge this will absorb any moisture for a short time until the gel gets saturated. I think I would just put up with the fogging.