While not an ergonomics expert, I feel that the design of the Ipad and other tablet devices is not ergonomic. Why? because you have to look down to use it, the height of the keyas is not likely to be optimal, and the screen position may make it hard to read.
I have purchased an iPad case and wireless keyboard made by Kensington, and it really helps make the iPad much more usable. I love the keyboard-it makes typing soo much easier, especially since you don’t have to switch keyboards for numbers and special characters.
My client and friend, steve Meagher of Site Solutions has released a video which discusses some steps you can take to make you iPad more ergonomic. Check it out here http://www.siteergonomics.com