A feature I always wanted to see in Snow Leopard’s Spaces was the ability to assign different background pictures to each Space in order to make them visually distinctive. Without that, it was sometimes difficult to tell which Space I was in.
This feature has found its way into OS X Lion, and it’s quite simple to set up, especially if you already know how to change your desktop background (easy to find in System Preferences under ‘Desktop & Screen Saver’).
To simplify things, first assign System Preferences to ‘All Desktops’ by right-clicking on the System Preferences icon in your Dock, selecting ‘Options’ and then ‘All Desktops’. This will save you some headaches if you’re changing multiple desktop backgrounds at once.
Then, navigate to the desktop whose background you want to change. Once there, change the background in System Preferences. Simple.
Using different backgrounds for each of your desktops will make navigating between them in Mission Control much easier – especially since Apple hasn’t yet implemented any way to rename desktops.
– Chris Searl