Because you asked - I think the main thing that impeded my ability to quickly understand Intercooler.js's functionality was the excessive use of jargon. I don't see why you even mention 'PVC', 'declarative' [1], 'REST-ful', 'HTML5-style bindings' [2], 'richer UX', etc. It all has meaning, but it hurts communicating what is really incredible about what you've created here: simplicity. The 'richer UX' also gets off track as if this is introducing AJAX to people who have never seen AJAX before. Certainly a legitimate audience, but it doesn't jive whatsoever with the developer target audience clearly visible in the rest of the material.

My suggestion would be "Simple HTML-based AJAX", and then an introductory value proposition statement below that that references the interoperability [3] of the framework and restates the main hook but with a bit more detail (HTML attributes instead of just 'HTML' etc. Maybe make the AngularJS analogy as well, that helped my understanding a lot).

I also really like the demo on the landing page. Very clever putting a link to the next page there.

[1] Not really jargon, but in my opinion implies something more idealistic like Prolog than the pragmatic simplicity you have here.

[2] I don't even know what this one refers to.

[3] Referred to as 'scalable' in your current landing page. The fact that this is a library and not a framework is really something I like seeing - far easier to start using in an instant.