Foxconn was the sole maker of the iPad so far. Apple is rumored to change that.
Foxconn has manufactured the iPad for Apple so far. According to Digitimes this might change for the iPad 3. Apple is rumored to add another maker for the iPad 3, hopefully reducing the supply shortage experienced with the iPad 2.
As reported the iPad 2 Plus aka iPad HD is thinner and has a higher resolution display. The iPad HD is supposed to be marketed to the professional market. I don't buy this rumor yet as outlined here. i just do not think Apple it is worth for Apple to release an iPad HD as a high-end iPad. It is of course possible, but the marketing and the positioning around this new iPad HD must be razor sharp to not confuse consumers.
More iPad 3 Rumors.