WebOS also has its own framework. As far as I understand this is about standard web applications (i.e. framework agnostic). F.e. you could build your app in jquery-mobile and make your app communicate with the device through a JavaScript API.

I asked this from Brendan Eich on Twitter. Response:

Still no core webOS src on http://github.com. We haven't had time or cause for Enyo. Having fun building non-O-O JS/HTML/CSS apps

https://twitter.com/#!/BrendanEich/status/174117089047621632

No, WebOS was a proprietary operating system with a proprietary framework that happened to run apps written in html/js.