There are some new rumors about Apple's 2nd-Gen iPad, that will use 5.6" and 7" AMOLED displays. According to the rumors, the iPad 2 will be launched at 4Q 2010. A new 9.7" version will also be released, with some "minor" changes, and will still use an IPS-LCD. The smaller iPads will mainly target the e-reader market.
While it's true that OLED costs are expected to drop, it's still unlikely that Apple will find a supplier that can make enough OLED displays. Samsung can't keep up with current demand for smaller displays (4" or less), and their new plant will not be ready by the July 2011. There are other companies working on new OLED plants (LG, AUO, TPO) but these will also not be able to meet Apple's demand.