The Times Online of London today is reporting that Lion Quality Eggs is now marketing eggs that tell you when they're cooked. The key is a thermal ink that shows up only after sufficient heat has been applied to the egg. Boil the egg and the second it's done, the ink appears on the side of the egg to let you know.
Unfortunately, if you like variety, you'll have to buy three dozen eggs. Each egg is only printed with one type of ink, so you'll have to decide whether you intend to eat them soft-boiled, medium boiled, or hard boiled. I don't know why they don't just print each one with all three inks, but I suspect it's to make space for that big logo on the side.
No word on progress in printing egg yolks for over easy, medium, or hard.
found at Gizmodo