Transactional memory appears promising for democratizing concurrent programming. Its potential lies in producing code that is extensible as atomicity is preserved under composition of transactions. This new abstraction raises several challenges such as the compliance of transactions with alternative synchronization techniques of legacy code and memory consistency models that favor transactional programming. The objective of the Second Workshop on the Theory of Transactional Memory was to discuss new theoretical challenges and recent achievements in the context of transactional computing. We report on some of the issues raised during this workshop.