Photomosaic software for linux?

I've been looking around for photomosaic software for linux, somethng that will create large (like 100 megapixel and up) photo mosaics.  Does anyone know if something like this has been written for linux?  I've tried JImage already, but as far as I can tell, it isn't built to scale to this kind of image size.  I used to know of a decent command line photo mosaic generator, but I can't seem to find the link for it anymore...