Apex physics is somthing that has been around for a while.
Apex physics is a new type of simulating made by the Nvidia dev team.
It Implements new ways of water flow/dynamic particles turbulence/destruction/particles.
Heres a vid of APEX used (Note the title only says physx but yhea thats the engine). http://www.youtube.com/watch?v=rbBnWLo3Ir0
APEX destruction could be used for the destruction of walls. and other small structures.
http://www.youtube.com/watch?v=8ztQX0C4wTE
APEX Cloth for things as curtains or clothings (Check mafia 2 apex cloth)
http://www.youtube.com/watch?v=I7ESwjlOZkY