Consensus on #maemo seemed to be:

• Setting up lots of infrastructure before there's content/desire is a bad idea, generally.
• "Design" sub-forum on tmo, moderated by wazd & timsamoff
• Stickies in that forum for best themes (pointing to maemo.org/downloads/), tools, tutorials etc.
• Can use forum features for polls, showcasing, blogging, whatnot.
• We could set up http://design.maemo.org/ as a redirect to that sub-forum, giving the "brand" aspects of the idea.