ArcScan is a mature product at this point. Though I know ESRI is providing access to the extension with all installations of ArcGIS Desktop and there is not much incentive for ESRI to work on an extension that is a "freebie", it would be nice to have ArcScan support some of the popular image formats that are out there. Currently the raster painting toolset does not suppot PNG, GIF, or BMP. All three of these formats are commonly used for index-color and bitmap (two-tone) images. ArcScan would be greatly improved by 100% support for these three file formats.