For those of us who use multi-monitors, this will surely be a good reason for Windows 8.

Via Neowin:

http://www.neowin.net/news/huge-multi-monitor-enhancements-coming-in-windows-8

For improved wallpaper support Microsoft is adding a few new features. Firstly, multi-monitor users will be able to select different desktop backgrounds for each of their monitors, and where needed and configured (for example with different monitor sizes/resolutions or even orientation) Windows will shuffle through images that it thinks are most suited to the monitor set-up. Also, you'll be able to set a specific option that spans wallpapers across multiple monitors for cool effects.