cpshop is a set of perl scripts created by Marty McKloskey.
You host the scripts on your server and use the admin screen to bring in your Cafepress basic shops and/or premium shop sections. You can use templates and filters with this to create a storefront to your liking.
These scripts are also handy for creating themed affiliate stores where you can display products from other people's shops as well as your own. All sales through any cpshop site still go through CafePress's shopping cart and fulfillment system, and affiliate credit for both the affiliate and original shopowner are tabulated automatically by CafePress.