I noticed today that some aerials on the maps in Michigan are shifted. Take a look here for an example. If you compare the north/south roads in the area both above and below the clear dividing line between the two different quality aerials, you'll see a shift of the roads by perhaps 5 meters. The effect may be greater in other areas. Without any way to really verify it myself, I'm of the opinion that the cleaner aerial image (the north side of the Permalink) is accurate and the other one is not, but I don't know that for sure. If someone wants to drive through an area similar to this and then compare their drive trace with the roads, we could figure out which is correct.
I'm just giving this as a warning before anyone makes too many adjustments on roads that are only off by a short distance (5-10m) as you may actually be messing up the road instead of fixing it if the aerial is incorrect. From panning around, this effect appears to only be an east/west shift and not a north/south shift, but that may not be true everywhere.
Edit: Here is another example. If you look at the GPS marks, the clear winter aerial is the one that doesn't match, while the blurry summer aerial does match.