How about with a tan/beige/khaki pencil skirt? I have a dark plum pencil skirt that I could easily envision it with too. How does The Limited style it on their site? (They always have the "Top Looks" link!)
On The Limited's website, they've paired the cardigan with 1) a solid white dress 2) white shorts and white button up shirt 3) white pants and a yellow tank (same yellow as in the cardigan). Helpful, eh? I like the idea of pairing it with plum! I'll have to try that, and maybe put a neutral top underneath?
I LOVE this cardigan! plum would be a great color with it, or navy. I'd also wear it with teal or aqua.