That's an interesting question, considering Britt, my heroine in MARRIAGE: FOR BUSINESS OR PLEASURE? has undergone a radical hair dye job for the US cover (out in Feb 2010.)
In the book, Britt is quite clearly a redhead. Nick, the hero, has nicknamed her Red since they were teenagers. And that is clearly depicted on the UK cover.
Now don't get me wrong, I love this US cover, it's gorgeous!
But why the hair colour change?
Hmm...guess it must be true. In the States, blondes do have more fun. :)