Recently, the first Workshop on Theoretical Aspects of Evolutionary Multiobjective Optimization (EMO) has been taking place on July 8, 2010 in Portland, OR, USA, co-located with the Genetic and Evolutionary Computation Conference (GECCO). Besides a brief presentation of the workshop talks, we mainly focus here on summarizing the results of the discussions. In particular, we present a list of open problems that has been compiled before and during the workshop by the participants. We hope that this overview of the latest forefront of theoretical research in the field of EMO will inspire future work and foster collaborations among the members of the EMO community.