The rumor behind the iPad 3′s delay was that Apple wasn’t able to get the high-resolution 2048×1536 displays they needed from Sharp at the price point they wanted.  LG and Samsung could supply the screens, but not enough with the quality that Apple wanted.  DigiTimes is reporting that someone who is familiar with industry supply sources is that instead of going with one of the companies, Apple is going with all three companies to supply the Apple displays.

LG will carry the bulk of the orders, then Samsung, then Sharp.

Another reason that the next iPad was delayed was that Apple needed additional backlighting to accommodate the high resolution display.  Taiwanese Radiant Opto-Electronics is reportedly going to be the backlight supplier for Samsung’s production, half of LG’s, and some of Sharp’s.

Source:  DigiTimes