Before I go any further, I would like to commend you for taking the lead in the Themes project. Also, I like the look and feel of the "Themes" subdomain — very simple and elegant.
I have some suggestions:
(1) Is there a way to create a separate Forum section to explore topics that will transcend the various themes — new and old. This would be more like the "CSS/Layout Forum" section in the main Tikiwiki page. I read somewhere that there is plan to migrate the latter here, anyway.
I understand there is aready a "Tiki Design" forum section but the way that forum is now going, it is more like an "ideas" forum section, rather than a Q&A Forum section that is more in keeping with the "CSS/Layout Forum" section in the main Tikiwiki page.
Both have their place as separate forums, I think. It is a good idea to keep them separate. And, as you stated, it would make sense if the "CSS/Layout Forum" section in the main Tikiwiki page migrates here eventually. The other possibility is just to start a new section here (then lock the other one there).
(2) I have just started reading the features of the new Tikipedia. [Kudos for the good work and I can empathize with what you stated somewhere how difficult to hack the whole thing to adapt it to Tiki.]
Aside from the overall appearance, I really like the plugin features. They may be the solution to the related questions I have been asking in the main Tike page forums in regard all sorts of issues such as page-specific layout customization and page specific insertion of randomized photos or text scripts using "module scripts" that are not accepted or not doable for example by the Dynamic Content System or the Banner plugin.
For now, I will ask my clarifications in the "New Themes", but as you mentioned those plugin features in the Tikipedia theme are adaptable to other themes, as well. Thus, it would be best eventually if there is a separate general forum section that will deal with Q&A clarifications that will be applicable to all themes.