Apple fans have been getting very excited over speculation that iPad 3 will be launched next spring with a display that has 5 or 6 times the pixel count of the current model.
According to Apple, the Retina Display has a pixel density so high that the naked eye can't differentiate between individual pixels on the screen (from 12 inches), which they put at around 300ppi (iPhone 4/4S has 326ppi). Currently the iPad 2, and iPad 1 for that matter, has 132 pixels per inch.
This leap in resolution would dramtically improve the iPad viewing experience, but according to an article from ExtremeTech (opens in new tab)we still have some waiting ahead. The technological developments follow a somewhat predictable cycle and according to Moore's theory, a chip or display will double its transistor count, and thus power or resolution every 18 months.
The evolution of production costs takes some time to reach a convenient level for mass production, with manufacturers setting up their assembly lines and adapting to the technological developments. This process suggests a "curve of innovation" that can estimate the release of new technologies with accuracy, and this theory, they say, has not failed in the last 35 years.
There have indeed been numerous reports that although a Retina Display is being looked at for the iPad 3, Apple's manufacturers are facing serious challenges with mass production of the screens.
So essentially, Apple can't afford to produce iPad screens yet as advanced as a Retina Display on a large scale, since the manufacturers are far from ready. Based on the projections using Moore's Law, 2013 will be the year when this becomes viable. But then again...rules are there to be broken!