Last week, eBay announced a few me-too social-network features allowing users to blog and share photos. Too bad it's not 2004. Meanwhile, Facebook is getting more serious about invading eBay's turf. Today, Facebook announced that developers can now write apps to search Facebook's Marketplace classifieds and create listings for users. Expect to see apps that, for a small commission, help users sell their stuff; eBay already has a ton of such apps, and they account for a large share of eBay's listings. Will this make Facebook's marketplace actually useful, though? The site's classifieds are already filled with offers for free iPhones and guides to telling if your man is cheating. If Facebook CEO Mark Zuckerberg can solve the spam problem, perhaps he'll add eBay CEO Meg Whitman to the list of prominent visitors calling on him with offers to buy a stake in his company.