"subsurf" is a modelling technique, not a render method. on the other hand, ATI introduced a hardware-based smoothing algorithm called TruForm [dx8] (
http://en.wikipedia.org/wiki/Truform ), but a very limited amount of games supportet it. nowadays, shaders have completely replaced it, as normal maps are faster, easier to control and work on all dx-based hardware, not only ATI cards. there was a counter-concept from nvidia, but it wasn't intorduced in games at all.