I imagine this depends on one's perception of "shift", but as someone who's been using the commercial Internet since the late 80's, in my view the world wide web only went through one fundamental shift - that was from static web pages to dynamic ones (CGI, at the time).

Programming tools, languages and paradigms (client side v. server side, MVC v. layered, and so on) have evolved for sure, but the WWW? Nothing fundamentally new since the early 90's when CGI made its appearance. The web works today as it did then, albeit with fatter pipes and obese page payloads.

http://en.wikipedia.org/wiki/Common_Gateway_Interface