I'm not sure I want someone working on a front-end component trying to optimize for a back-end process without realizing the full impact of these front-end changes. I'm assuming/hoping in this case it's just a "hey, this is something fun I did."
Correct me if I'm wrong, but if the combined size of an image and its complementary CSS file is less than the size of a 129kb CSS file with "CSS3 images", then don't you essentially lose the benefit of reducing server load?