If you’ve got a new iPad, one of the first things you’re likely to notice is that graphics on the Web look fuzzy when next to crisply-rendered text. Graphics could look blurred on the iPad 2 as well, but it was not nearly as contrasted as on the new iPad. I don’t think many people plan to go through their site and update all the pictures, screenshots, and etc. found in their past articles. But one simple thing that websites can do to improve their look on every iPad is to use SVGs or upscaled PNGs for their header and sidebar images.
For example: on Sean Sperte’s site, Geek & Mild, the ampersand logo is an SVG — and so it scales well and looks crisp on any screen.
Here on shawnblanc.net I upscaled the “shawnblanc” image. Meaning the source image is exactly three times larger than the size it’s displayed at (777×138 and 259×46 respectively). It looks nice and sharp on an iPad 3.
I think a good rule of thumb for what graphics you should bother updating or not is simply this: if you want people to read it, or if it’s a critical component of your site design, then update it to look crisp on a Retina display.