Growing indications this may well be on the cards, sporting a retina display.
This isn't the only source but - http://forum.tipb.com/ipad-3-forum/214970-ipad-3-october.html
I've been thinking for a while Apple could differentiate the iPad further with a higher spec version for those willing to pay for a more expensive version. A cut down version of the iPhone I find harder to imagine but yeah, iPad HD anyone?