Yup, Polymer is doing exciting stuff – the declarative native UI components in Supersonic are actually implemented using web components (meaning they're really framework independent), and we utilize their polyfill since the web component spec is not supported in browsers yet. You can see the source code at https://github.com/AppGyver/supersonic/tree/master/component...

We didn't embrace Polymer more fully for various reasons (like it being a very WIP project still), but the Polymer web components should all work fine with Supersonic apps.

Disclaimer: AG employee here. :)