If you want to try this yourself, I've written full instructions on my blog.
This is an iPad 3 as an external display for my iMac, via Air Display. Hi-DPI mode is not enabled in this case, so the iPad's Retina Display acts as a 2048 x 1536 monitor - which makes things a bit tiny on a screen that's 9.7 inches on the diagonal!
For comparison, I've shown the same size (in terms of pixel dimensions) of browser window on a 1366 x 768 MacBook Air (11" diagonal) screen. The choice of website was not accidental.
The iPad stand is an oak WoodPad. Items supplied for size comparison are, from left:
- Ohto Promecha mechanical pencil (0.5)
- Ultra-fine Sharpie
- One Euro coin
- Apple iPhone 4 (or maybe 4S; I forget which)
- Just Mobile AluPen stylus