From Pixologic’s website:
You can already use DynaMesh to build shapes that serve as a base mesh for sculpting. Now, you can alternatively define PolyGroups on your model and then simply replace those areas with a new mesh! When doing this, ZBrush merges the new element into the support mesh by bridging the polygons at the insertion boundary. In this way, your model’s topology is changed only where new details have been added.
These and a host of other new tools that are constantly updated and improved, make ZBrush extremely versatile. Its expanding toolset promises to continue to simplify complex digital sculpting tasks.