Recently the retina MacBook Pro was released at WWDC 2012. It has a resolution of 2880 by 1800. This makes websites look really bad if they haven't been optimized for the new high-res display, as noted by Marco Arment. What are some thing I need to do to optimize my website for retina displays?
You'll need to mix high resolution graphics, css and things like @font-face, obviously if you create a website specifically for retina displays it will create a lot of data to download with larger images etc, but what you can do is using CSS create optimised verstions for retina and non-retina visitors.
There are some great tutorials online including these: