The only problem with that solution is that it introduces an issue in regards to the background showing through on the right hand side of the navigation.
After talking a little more with Keith, we’ve managed to come up with what seems to be a working solution (and by we, I mean Keith, I only changed one line of his proposal): http://jsfiddle.net/joshnh/UazCp/
Basically, the background colour and pattern has been placed on the unordered list, and the list items are given a white background. That background is then removed when given a class of active.
What are your thoughts? Any problems with this approach? Any ways to improve it?