Web 2.0 provides the technological foundations upon which the crowdsourcing paradigm evolves and operates, enabling networked experts to work on various problem solving and data-intensive tasks. During the past decade crowdsourcing grew from a number of purpose-built initiatives, such as Wikipedia and Mechanical Turk, to a technique that today attracts and engages over 2 million people worldwide. As the computing systems are becoming more intimately embedded in physical and social contexts, promising truly ubiquitous computing, crowdsourcing takes new forms. Increasingly, crowds are engaged through mobile devices, to capture, share and validate sheer amount data (e.g. reporting security threats or capturing social events). This workshop challenges researchers and practitioners to think about three key aspects of ubiquitous crowdsourcing. Firstly, to establish technological foundations, what are the interaction models and protocols between the ubiquitous computing systems and the crowd? Secondly, how is crowdsourcing going to face the challenges in quality assurance, while providing valuable incentive frameworks that enable honest contributions? Finally, what are the novel applications of crowdsourcing enabled by ubiquitous computing systems?