From their About page: "This website layout was humbly borrowed from Twitter original layout, since we believe we are creating value for its own community from which we belong."

I wonder how Twitter feels about sites replicating its layout. Companies using your API is great, but I'd get uncomfortable if a company made it look to unattentive users like my company was involved with their product. (In this case, I just wouldn't want to be associated with that grammar).