Hi Jim,
I assume you meant identifying the pixel value of certain raster dataset in a raster catalog?
There is a workaround for that. You can
1. Go to ArcCatalog, select your raster catalog in Catalog Tree view;
2. Activate the Contents tab on the right to see each individual rasters in the raster catalog;
3. Drag and drop the raster dataset you want to identify to ArcMap;
4. Then it will be displayed as a layer with the name of <your catalog name>\Raster.OBJECTID=<number>, you can use the identify tool to check the cell size just like normal raster dataset.
However if you in ArcGIS 10, it is better to use mosaic dataset to manage your images. Mosaic dataset support identify cell size on the "image" layer of it.
Hope it helps.