It depends on what type of animations you are leaning towards, because a single jQuery plugin to cover every single type of animation would likely be more of a library and too big for most web projects at this time.
KineticJS is popular as an HTML5 Canvas framework that lets you create lots of animations, transitions, layers, and event handling which are some important things. I linked the site above so you can explore it a little and see what types of games/projects people have made with KineticJS and so you can get a feel of the type of animation for which it can be used.
Another animation library/plugin is CreateJS which has a whole suite of content creation frameworks, the one you probably would be most interested in is TWEENJS, which supports some good stuff like CSS properties, and has a few sponsors already.
One drawback is that both of these animation frameworks are not based on jQuery but are based on JavaScript. This is good and bad because both frameworks don't depend on jQuery but you could probably use jQuery for get elements more conveniently.
Most frameworks are for JavaScript, but there is the standard .animate()
method in jQuery that may be limiting compared to a full extended framework. It is more integrated into jQuery and you can animate the CSS properties though, so it all depends on how much you need and what you need exactly. Let me know if these don't suit you, and I'll try to find something different.
EDIT:
If you prefer something from Adobe, which it seems that you might, then take a look at Collie, which is another framework that uses the HTML5 canvas and DOM to create animations using JavaScript.