Here's a question for you.
I cant find the microfocus adjustment spec listed on the canon site, although I see it in the reviews. On the canon site, the Chromatic aberation lens adjustment seems to be included in the EOS software.
Canon's exclusive Lens Peripheral Illumination setting takes into account any light falloff in the corners of the frame and corrects it, making for a perfectly exposed image. Correction data are detected automatically on a number of Canon EF lenses and can be entered manually through the included Canon EOS Utility software.
If the microadjustment is in the software provided, I wonder if you could use the software to adjust the existing 40d or 30d? It wouldn't seem that there would be existing memory locations for multiple lenses, but there might be, considering people have said that when they send their cameras in the service center sometimes asks for more than one lens.
In any case, a round of applause to someone who points me to the microfocus reference as shown on the canon official site.
50d, 70-200 2.8L IS, 24-70 2.8L, 85 1.8 USM, 17-85 IS EF-S, 50 1.8, 430EX.