A Japanese blog, Macotakara, is claiming that a new generation of iPad is to be released in March 2013. The report provides no technical specifications on the new iPad, but says it will be thinner and lighter.
The same report says that a 2nd generation of the iPad mini will enter testing soon. The new mini will have a 2048 × 1536 pixel (326ppi) Retina display and the same A6X processor as in the current iPad 4th generation.
If true, this report would indicate that Apple has moved to a 6 month product cycle as a normal matter, perhaps to better compete against Android and Windows products.