Generalized Quantum Theory: Overview and Latest Developments
  The main formal structures of Generalized Quantum Theory are summarized. Recent progress has sharpened some of the concepts, in particular the notion of an observable, the action of an observable on states (putting more emphasis on the role of proposition observables), and the concept of generalized entanglement. Furthermore, the active role of the observer in the structure of observables and the partitioning of systems is emphasized. 
Thomas Filk, Hartmann R\"omer
quant-ph physics.hist-ph