I love WordPress 1.5 and the community. It’s really amazing. I will be helping a company develop a site with regisered users and a paid/free content section. It seems like WordPress is great for blogs but am leaning to using Drupal 4.6 especially with its commerce API (PayPal framework, etc.)
Have you looked into Drupal as a CMS for this? 4.6 was just released a few days ago and some WP themes are being ported. Plus and minuses to both but that is how I am looking at it now.
WP for Blog
Drupal for CMS
Would be great to have a merged Drupal + WP