necessary. Some of the important ingredients which have to be considered in a consistent manner are

-   the initial conditions and the initial nonequilibrium dynamics,

-   the treatment of the phase transition and hadronization, as well as the right degrees of freedom,

-   viscosity effects in the initial partonic as well as in the hadronic stage of the evolution,

-   hadronic rescatterings and freeze-out dynamics.

We notice that part of these have been pointed out to be of importance especially for the understanding of the HBT results [@Pratt:2008sz; @Lisa:2008gf; @Broniowski:2008vp].

Combined microscopic+macroscopic approaches are among the most successful ideas for the modeling of the bulk properties of HICs [@Andrade:2006yh; @Hirano:2005xf; @Nonaka:2006yn]. Recently, a transport approach that embeds a full (3+1) dimensional ideal relativistic one fluid evolution for the hot and dense stage of the reaction has been developed and first results are convincing [@Steinheimer:2007iy; @Petersen:2008dd]. This hybrid model inherits the advantages of the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model for the dynamic treatment of the initial and the final state by taking into account event-by-event fluctuations. Furthermore, the hybrid model allows for a dynamical coupling between hydrodynamics and transport calculation in such a way that one can compare calculations with 