According to CNET, there are some sources who have informed them that manufacturers are finding it very difficult to create the high resolution 2048x1536 resolution display in large quantities that Apple requires. Though they will start production in November it is quite unsure whether they will be able to make enough to cater to Apple's needs.
If the manufacturers are unable to make the required number of displays then they will make a 1,600x1,200 resolution display.
Detailed information on this is currently unavailable but we will try to get it very soon.
Until then hope that the manufacturers can make enough display so that we can have an iPad 3 with a better resolution (264 PPI [pixel per inch] -- twice than the 132 PPI on the iPad 2).