Twitter founder Biz Stone has officially announced the launch of Jelly, a question-and-answer-based search engine for iOS and Android. It's an app that lets you ask questions, push them out to your network, and get rapid responses. "If you have a question, there’s someone out there that knows the answer," Stone says in a video accompanying the official blog post. The app places a heavy emphasis on visuals, encouraging users to post photos and ask questions about what they're seeing.

In June, The Verge broke the news that Stone's stealthy startup was focusing on Q&A. Jelly builds on work Stone did as an adviser to Fluther, a Q&A service whose team was acqui-hired by Twitter in 2010. Ben Finkel, who co-founded Fluther, co-founded Jelly with Stone. Both apps tap social networks to deliver quick answers to your questions. In a quick tour through the app, we found that after logging in through Facebook and Twitter, we saw questions about business, Xbox controllers, and where to vacation in Ireland. It's a more personal, immediate take on Q&A than something like Quora, which was born on the desktop and encourages lengthier responses.

The trouble with most Q&A apps is that smart people tend not to sit around all day waiting for questions to answer — and the people who do tend to offer answers that are irrelevant, or worse. By tapping friend networks, Jelly is placing a bet on the altruistic side of human nature. But just ask Yahoo Answers — getting people to stop what they're doing and offer a helpful response is often harder than it looks.