You’ve probably seen this already, but it’s really worth bearing in mind: when you’re scaling up JPGs for retina display you can safely reduce the image quality by quite a lot—to the point of getting the exact same file size as a higher quality image that’s half the size.
Trent offers some excellent advice for dealing with the effects of the iPad’s retina display on your websites. That advice is: don’t panic.
Luke rounds up some of the alternatives to bitmap-based images—an increasingly important topic for “resolutionary” “retina’ displays (bleurgh!).