Jquery - abstracted away tons of cross-browser inconsistent behavior, both with the dom and javascript, and added new selectors to make dom manuplation easier. I think there was a reason it was adopted as fast as it was, it really was a 10x improvement in working client side.
Boost for C++ likewise. It was a necessary bridge in the long wait for C++0x, but once the language started updating again it's no longer as necessary.
Absolutely it has run its course. There are a now a litany of javascript frameworks to suit the variety of projects being done in javascript (both server and client side), and browsers are now far more compatible (I think partially because browser makers realized with the popularity of jquery how in demand that was) but I was only recognizing what an innovation it was at the time.
