Yeah and this is becoming increasingly important. image.png, image@2x, image~ipad.png, image@2x~ipad.png...
"While some of the apps have received additional features, it seems likely that the increase in size is mainly down to the huge graphics needed to fill the new iPad's 2048 x 1536 Retina Display. It's worth remembering that these are only download sizes, and once installed the apps may be even larger. Regular apps will likely receive a similar bump in size once developers update them with hi-def graphics"
"iPad apps up to five times larger..."
However, current PNG compressors are really good at optimizing flat color areas, gradients, and lines. It seems to me like most images would get only a relatively small increase in size due to this upsizing (1.5x-2x).