Data URIs make CSS sprites obsolete
CSS sprites were a solution to the problem of multiple HTTP requests to download multiple images. Data URIs allow you to embed images directly into your CSS files, solving the same problem in a much more elegant and maintainable way.
I hate working with sprites, but I do it because it is or should I say, was, the best way to increase the loading speed of images.
Since a few minutes ago I never heard of Data URIs, but it is great and I think I will try it out very soon. You should, too.