The document describes the plista Recommender Challenge Hackathon. It provides information on: - plista's recommendation and advertising network which delivers over 8 billion impressions per month. - The hackathon challenges participants to develop a recommender that implements plista's API to be evaluated on its success in tracking recommendations. The best recommender that is scalable and works for industry will win. - Participants can use various programming languages and machine learning libraries. Starting involves registering, implementing examples from the wiki, and getting real-time recommendation data from plista to display on publishers. - Recommender ideas suggested focusing on implicit feedback, incremental updates, and handling cross-domain recommendations within publisher slices of data.