One of the newest players in the Facebook storefront game reported a red-hot first two days.

ShopBuilder, launched by U.K.-based do-it-yourself website builder Moonfruit, officially launched October 19, and more than 4,500 storefronts went live within the first 48 hours, with 30 percent of those coming from the U.S., according to the company.

That large number suggests that Moonfruit simply extended existing clients’ web storefronts onto Facebook pages enabled for commerce. Then again, the 4,500 is dwarfed by the nearly 4.2 million websites that the vendor has been responsible for.

Moonfruit described ShopBuilder as an out-of-the-box e-commerce solution for Facebook, websites, and mobile, targeted toward small businesses and individuals.

ShopBuilder is also integrated with PayPal, allowing users to begin accepting funds via the payment platform immediately by registering an email address, without the need for a merchant account.

Moonfruit said integration with eBay and other online marketplaces will happen soon.

Here’s how Moonfruit describes ShopBuilder:

The Moonfruit ShopBuilder automatically publishes your shop onto web, mobile, and into Facebook. You only have to set up your shop once.

It offers a mobile optimized checkout for phone shoppers integrated with PayPal. It allows you to push your products into your Facebook and Twitter stream. It allows your customers to like and tweet their browsing and buying habits. It can be designed and published by you like every other Moonfruit tool. It’s even free.

The free version of the application includes advertisements, while ad-free versions of the app cost money.

Readers: Would you want to launch a Facebook store that included ads from other brands?