Its good to keep abreast of technologies especially when they are being pushed into the mainstream by player like Google and Facebook.
these two libraries seem to have the same goal with different approach. A reusable component based document object model.
Google Polymer - " From <a> to <select>, elements are the building blocks of HTML. But modern applications have outgrown these built-in elements, forcing app developers to rely on JavaScript frameworks to provide dynamic, custom behavior. The resulting apps are frequently complex and monolithic; a component developed for one may not work in another.
Polymer puts elements back at the center of web development. With Polymer, you can craft your own HTML elements and compose them into complete, complex applications that are salable and maintainable."
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Just some awareness.
Al