I personally don't want to see "retina displays" in MBP.
1 - It'll kill battery life. See what happened with iPad 3. They needed a bigger capacity battery just to keep up with iPad 1 because they had to boost backlight so much.
2 - 1440x900 on 13", 1680x1050 on 15", 1920x1200 on 17" is "retina" enough for me. Please don't tell me your eyes can resolve individual pixels in a 1920x1200 17" screen. Mine can't. Doubling the pixels with HI-DPI icons would not add that much detail, and surely wouldn't add desktop space. A 2880x1800 display in a 15" would give you the same desktop area as the current 1440x900, wich is ridiculous.
3 - Too much unnecessary work from the graphic card. See battery life. 3D gaming would be unthinkable at those resolutions with current mobile graphics, so you would have to lower the resolution and the panel would have to scale a lower resolution. LCD screens look bad not running their native resolution, period. So much for image quality.
1. Not necessariliy. The iPad has a quad-core graphics processor that may drain the battery. Ivy Bridge has integrated graphics that support retina resolutions, so it should handle battery consumption better.
2. Yes, it will add lots of detail. Fonts look a little blurry on the screen of current Macs due to que sub-pixel rendering technology used by Apple (Quartz). You should have noticed that fonts look much sharper on Windows due to ClearType sub-pixel rendering (although fonts look distorted too and not exactly as they appear on a printed page). A retina display would make fonts look sharp on a Mac screen using Quartz.
As for desktop space, tale a deeper look at 9to5Mac. It says that the user will be able to choose if it wants a larger or smaller desktop using retina resolution.
3. Standard resolution games should run fine on retina displays as they do on retina iPads.