Hitachi has used the CEATEC expo to unveil its super high resolution next generation IPS display for tablets. The 6.6-inch 1600x1200 display packs in 302ppi, which compares very favorably with the iPhone 4 Retina display which packs in a slightly higher 326ppi. The new Hitachi display does, however, significantly exceed the 132ppi of the 9.7-inch 1024x768 IPS iPad display. It is also much sharper than the display 169ppi display in the Samsung Galaxy Tab.
The new Hitachi panel also delivers an 800:1 contrast ratio and 400 nits of brightness and, like the iPad display, has a 4:3 aspect ratio. Hitachi did not offer a timeframe as to when tablets incorporating the display may begin to ship. [via Engadget]
Read more: http://www.electronista.com/article...26ppi.in.apples.retina.display/#ixzz11ZuprqgY
Still highly doubt we will see this in an ipad any time soon, but the 4:3 ratio and the size would lend themselves to a 7" ipad (well a 6.6" ipad).
However I imagine the cost of these panels is beyond any reasonable pricing framework that could work in an ipad for a good while yet.