<http://www.adobe.com/products/premiere/encore/features/?view=all>

That's the only feature listing available right now...some stuff is listed as new, some listed as enhanced.

I know that the Flash/SWF output gives you a few more customization options (like a page background, for instance...which you could do in the HTML code previously anyway). And the Blu Ray menu stuff is much improved.

Also, Dynamic Link goes a little further now and allows you to import Premiere Pro sequences without rendering, the same way you could do before with After Effects compositions. Very cool, good for time savings and preserving disk space.

I don't know any other big "wow" factors, probably not too many since it's a secondary application to Premiere Pro now.