Does it work with ArcGIS 9?
Yes. Only the install script needed to be upgraded for ArcGIS 9 and no new version number of the actual extension was generated. A zip file with the install script that will work with ArcGIS 9 has been available since May 2004. In the event that you still have problems with the install, you may need to do the following in ArcCatalog so ArcGIS will recognize the file type. From the tools menu, select options > raster > file formats > advanced > add new raster format, and point to bsbf.dll found in c:\program files\common files\esri\raster\user\lib\ntx86\rasterformats.