http://mattgemmell.com/2012/04/06/ipad-as-a-mac-retina-display/
With the recently-released new iPad (3rd generation) being equipped with a Retina Display, thereâs now only one major category of Apple device without a very high resolution screen: the Mac. Weâre sure to get a Retina Display Mac before too much longer, but you can actually preview how OS X may look on such a device right now.
Hereâs what youâll need:
A Mac, running OS X 10.7 (Lion) or later.
A new iPad (3rd generation).
Air Display from Avatron, on both the Mac (free) and the iPad ($10).
The Xcode Developer Tools (a free download from the Mac App Store), and an Apple Developer account (also free).
A local wi-fi network, that both the Mac and the iPad are connected to.
