Basically any combination of frontend toolkits has it included somewhere, so you don't even have to worry about doing that. It's the default for Joomla and Wordpress and there are a measurable amount of functions that take care of the gruntwork and normalize utility across browsers.
On top of that, the amount of JS projects relying on jQuery as a foundation is staggering. The secondary market has tools built around the jQuery ecosystem and the project as a whole does an excellent job at marketing and advocating.
I personally see the next generation in such avantgarde stuff as Googles Polymer (pretty amazing) but until everyone has moved to SPAs and web components - which is not happening any time soon - but until then it's not the worst idea to familiarize yourself with the concepts and the utility funcitons of jQuery.
My 2 cents.