This is in reply to a previous question today (sorry I have not worked out how to reply to specific post). Archival imagery (such as Bing) has usually been processed and georeferenced/orthorectified (although to variable degrees depending on the source) prior to publishing. The post earthquake imagery provided by DG will have had minimal such processing undertaken on it as this takes time and effort and obviously DG want to just get the imagery out there for people to use ASAP. Alignment of this imagery to existing map layers will not be a straightforward shift in one direction due to the effect of elevation/terrain and satellite capture angle. My advice for this type of imagery would be to continually adjust the imagery to available/reliable map information as necessary - in one area of the image you may only need to adjust by say 10m to get a decent alignment - other areas may require a 100m shift. For the archival (e.g. Bing) imagery there can still be some alignment issues - this imagery will may have had systematic corrections but no manual input using ground control points (which is required for really accurate orthorectification).
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