Is it possible for someone to outline the actual workflow for doing this (aka from the beginning)? I have the same issue, except with Quickbird satellite imagery, however I am not very proficient with Arc10. At all. Thanks so much!!
If you open the Catalog Window in ArcMap, and right click on the mosaic dataset, and select Properties > Defaults tab, there is a Default Mosaic Operator there. It should be set to First by default. Try switching it to Max. Or you can change the footprints using the Build Footprints tool as Gordon suggested (make sure you uncheck Skip Overviews if you have already built them). His suggestion may be faster than mine if you are displaying large amounts of data.