My new boss went to a speech where Deliverance, a kind of proxy allowing to add skin to any html output on the fly, was presented. He decided to use it right after that, no matter how young it is.
More here :
http://www.openplans.org/projects/deliverance/introduction
In theory, the system sounds great when you want a newbie to tweak your plone theme without having to teach him all the complex mechanisms behind the zope products. And apply the same theme on a Drupal web site in one row.
But I don't believe in theory, and would like to know if anybody tried this out in the real world :-)
Having used Plone professionally for the last 4 years or so, and Deliverance on 4 commercial sites, I would advise all new front end developers (and old hands alike) to use Deliverance to theme Plone sites.
It is much easier to learn (a couple of weeks Vs couple of months) and potentially much more powerful than the old, confused, methods - few of which you will still need (and even then at a much later point in the life of the site).
Not only that, but it uses XPath and CSS selectors and can be used on non-Plone sites, so the time invested is easily transferable.