The iOS 5.1 beta describes three different processor variations, making reference to "/cores/core.3," as well as "/cores/core.0," which identifies a single-core CPU, and "/cores/core.1," which identifies a dual-core processor.
Based on Apple's naming convention so far, Gurman says, ".cores/core.3" would refer to a quad-core chip. The rumor is that such a quad-core processor would be called the A6 and be used in the expected iPad 3.
"Apple leaving references to quad-core chips in the iOS 5.1 beta is notable because iOS 5.1 is the software currently being tested against the third-generation iPad," Gurman wrote. "We cannot conclude that due to iOS 5.1 including quad-core processor references, Apple's next-generation iPad and iPhone will include a quad-core chip, but it seems reasonable based on Apple starting with a single-core chip in 2010 and moving to dual-core in 2011. A quad-core chip in 2012 would fit the pattern."
The latest speculation indicate the release of iPad 3 in March 2012 and iPad 4 in October, although it sounds had for Apple to release two proucts within 6 months.