Since February, Facebook has doubled its ad rates for sponsored groups from $150,000 to $300,000 in the US, reports ValleyWag which has obtained Facebook’s PowerPoint rate-card deck. Facebook now says it’s the top photo site. The minimum sponsorship remains $50,000, and Facebook claims the click-through rate is 20 times that of banners. This higher fee means the number of homepage links and sponsored stories advertisers get also doubles.