I seriously doubt it. You only remove 1 extra request with this technique. The main advantage is that you don't have to maintain a sprite image (but using this without some tool would also be cumbersome).

IMHO one saved request isn't work doing the same thing twice. And MHTML (http://www.phpied.com/mhtml-when-you-need-data-uris-in-ie7-a...) doesen't come as a saviour either, as you have to duplicate all images in the CSS, which increases the size of the CSS significantly (if it doesn't you are probably better off using "old fashioned" techniques.