No. Errr, it depends on the screen .
My 13" MacBook Pro is 1280x800, my iMac is 1920x1200, my cinema display is 1680x1050. As for the new MacBook Pros they are 2880x1800 for the retina displays, 1280x800 (13") and 1440x900 (15") for the non-retinas. So maybe a 1280x800 and a high resolution version would be enough?
OK, but all we need is the biggest screen sizes in 4x3 and 16x9.
People who have a lower resolution screen can still put the pic on. It will downscale automatically, right?