With the release of ArcGIS 10.1 available, I am sure many of you are wondering about the compatibility of the mosaic dataset in the new version, and its backwards-compatibility to the previous version.
A mosaic dataset that was created in ArcGIS 10.0 can be read in ArcGIS 10.1, but it cannot be edited. If you wish to edit the mosaic dataset, you can use the Upgrade Dataset tool to upgrade your data to be compatible with 10.1.
A mosaic dataset that was created in ArcGIS 10.1 can be read and modified within 10.1. However it cannot be used at all in ArcGIS 10.0. If you plan on reading your mosaic dataset in both 10.0 and 10.1, then it is better to leave your mosaic dataset as a 10.0 version since both versions can still read it. If you plan on editing your mosaic dataset it is probably best to edit it in 10.0, and then you can read it from either version. Or you can just keep both a 10.0 and a 10.1 version of your mosaic dataset.