You now have a new way to make themes for Plone, where do you go from here?
The best way to learn is by doing, so your next step should be to take one of your existing designs and map Plone into it.
If you don't have any themes yourself, a great site for free designs is oswd.org (Open Source Web Design). Here are some great themes you can download to get you started:
Invention (http://www.oswd.org/design/preview/id/3293)
Bitter Sweet (http://www.oswd.org/design/preview/id/3569)
Transparentia (http://www.oswd.org/design/preview/id/3515)
Remember that if any of these themes are missing ids for easy mapping in the rule file, just add them in the HTML.
Have fun with your new-found theming superpowers!