Since many users will continue to access the WWW through 9600 baud modems, I
believe that "funky tricks" to enable progressive disclosure of images are
still necessary.
One of the flavors of JPEG lets you stack layers of an image into a file
which, when streamed in, allows the image to "fade in" much nicer than the
Netscape interlace enhancement. IBM was, to my knowledge, the only company
that has developed a compressor/decompressor for this JPEG flavor, which
they dubbed JPEG Express.
In a recent 'corporate restructuring,' IBM dropped support of this product.
-- Alan