Over the next 10 years, we anticipate that personal, portable, wirelessly networked technologies will become ubiquitous in the lives of learners--indeed, in many countries, this is already a reality. We see that ready-to-hand access creates the potential for a new phase in the evolution of technology-enhanced learning, characterised by "seamless learning spaces" and marked by continuity of the learning experience across different scenarios or contexts, and emerging from the availability of one device or more per student. The challenge is to enable learners to learn whenever they are curious and seamlessly switch between different contexts, such as between formal and informal contexts and between individual and social learning, and by extending the social spaces in which learners interact with each other. In this paper, we review the potential of mobile learning research for designing seamless learning environments that can bridge both formal and informal learning, present a research agenda and discuss important methodological issues that concern research into formal and informal learning.