My 2005 stamp isn't on a chip, it is on the back side of the actual circuit board in the area right under the battery. When you remove the battery it is on the right side, and is stamped vertically (rotated 90deg counterclockwise from normal).

I have a feeling I should be sending my unit in for warranty repair or replacement. I'd love to keep it and wait for a permanent soft fix for this problem, but if one never surfaces from Nokia or elsewhere I will be dealing with this until the 820 comes out in 2009.