[quink]

I'd be interested in seeing these results with SVG.

There's a lot of commonality between the images, http://g-ecx.images-amazon.com/images/G/01/common/sprites/sp...

Even with Base64 encoding, much of that commonality would remain and thus I'd think that if you had all these sprites as SVG in a single file, as Data URIs, gzip would do a very good job indeed on the CSS file.

In a PNG sprite I wouldn't be so sure.