The second ACES-MB workshop brought together researchers and practitioners interested in model-based software engineering for realtime embedded systems, with a particular focus on the use of models for architecture description and domain-specific design, and for capturing non-functional constraints. Eleven presenters proposed contributions on domain-specific languages for embedded systems, the Architecture Analysis and Design Language (AADL), analysis and formalization, semantics preservation issues, and variability and reconfiguration. In addition, a lively group discussion tackled the issue of combining models from different Domain Specific Modeling Languages (DSMLs). This report presents an overview of the presentations and fruitful discussions that took place during the ACES-MB 2009 workshop.