Retina display Macs to come?

Mac OS X Lion Developer preview 2 included ultra-high resolution backgrounds, which were 3200x2000. Some of the icons were 1024x1024, instead of the normal 512x512. This hints that there will be Macs with retina displays! It seems like a good idea. It started with the iPhone 4, then came to the iPod Touch 4, it'll appear on the iPad 3, and now on Macs!