One of my favorite parts about the new Mac App Store is that it is "buy one, run everywhere" just like iOS apps on the iPad or iPhone/iPod touch. It has always been the case that you can buy an app at the iOS App Store and use it on all of your iOS devices.
"Desktop" software has often been frustratingly limited to one or two computers. I'm thinking especially of the new Microsoft Office suite, but there are many, many other apps (especially ones from Adobe) which ties a license to a single (or sometimes two) machine.
If you buy, say, The Incident for Mac for $3 from the Mac App Store, you can use it on all of your Macs.
Simply launch the Mac App Store on your second (or third or fourt
