Originally Posted by Thunderbird
It basically allows you to setup monitors add resolutions and so on while you are in X. This is basically similar to nvidia's dynamictwinview which they have offered for a while. The main difference is that xrandr 1.2 also allows rotation of individual screens.
And it would probably be less buggy than twinview. Right now, I'm struggling to find out why the hell twinview is treating it as if I had turned off ConstantDPI. I plug in a second monitor and get nvidia-settings to add it (that's another thing xrandr will do much better - I'll be able to script it instead of having to manually use some crappy GUI), the number of pixels go up, but as opposed to Appendix B, the screen dimensions don't change, and hence the DPI goes up to something stupid like 256x128, and all my fonts and movies become squashed.