Macotakara relays a Chinese ZOL report that claims "according to my inside source, iPad(5th) may be released in March, 2013."
A rough translation:
Source told that, design of this new iPad will be like iPad mini in detail, and be thinner and lightweight. (The expectation comes to have a small 4mm in height, 17mm in width, depth 2mm). To convey a different article, trial production of iPad mini (2nd generation) has been started. LCD display is 7.9 inches, it (326ppi) 2048 x 1536 pixels, it seems that will be equipped with a A6X processor such as iPad (4th generation).
Its recently been speculated that Apple may be moving to a semi-annual release cycle for its products which would see the iPhone and iPad receive one major and one minor update each year.