In Europe (and I expect the US, too) you no longer have to copyright your designs and logos, as they are automatically copyrighted.
ETA: Copyright - Claiming & Enforcing Copyright - Basic Facts about Copyright
Thanks for the information. Although this brings up something else I've always been wondering about. Take the Hermes Birkin, for example. That design has been copied all over the place, albeit without the Hermes logo. I even noticed one in Debenhams some weeks ago. Are those illegal or are manufacturers exploiting a loophole somewhere?