NaNoWriMo 2004 is gearing up for this year with a brand-new web site powered by Xoops, an Open Source PHP-based content management system. I'm no longer affiliated with the NaNo technical team, but I'm not surprised they threw out the old site in favor of a full-fledged CMS. I had built the site they used the past two years with phpBB, and wrote the front page CMS, excerpt posting and word count facilities myself using phpBB's templating engine and user account system as a base. The result worked well enough, but extending the site with new features required too much developer involvement. I'm not familiar with Xoops specifically, but it's clear NaNo.org could benefit from a real CMS's features.
Speaking of NaNo, check out No Plot, No Problem! by NaNo founder Chris Baty.
Speaking of Open Source CMSes, Jeffrey Veen has a rant worth listening to. Some of these are very difficult problems to solve, especially by volunteers with limited free time, but they're good points of focus. Also includes some follow-up comments of mixed quality.