The M?obius modeling environment is an extensible framework for discrete-event system analysis that allows multiple formalisms and solution techniques to easily interoperate, and new modules to be easily added. The basis of the framework is an abstract functional interface that defines the behavior and data to be shared among modules. New formalism and solver modules continue to be added to the tool. This paper describes recent additions to M?obius, including a fault tree model definition formalism, a model composition formalism based on action synchronization, improvements in reward model definition, and additional lumping capabilities in the symbolic state space generator.