USGS Has Been Busy
SEAWAT Version 4 was released last month. The major new feature is the ability to simulate heat transport.
The Conduit Flow Process (CFP) was released recently. It allows for the simulation of karst features (conduits) in MODFLOW2005.
GSFLOW is a new surface water/groundwater model. The groundwater part is MODFLOW2005 and the surface water is PRMS (Precipitation-Runoff Modeling System).
None of these new versions are in Groundwater Vistas yet. The new MODFLOW2005 and SEAWAT will be added first, followed by CFP, and finally GSFLOW. The latter will take quite a while to implement.