I've just installed an instance of WP 2.8.4 whereby the software is in public_html/wordpress and in anticipation of multiple blogs, $table_prefix as well as WP_CONTENT_DIR have been set at install time.
WP_CONTENT_DIR points to a peer directory public_html/oo_blog, where I'd copied the appropriate files. Everything seemed fine until I added a custom theme. At that point it became clear that WP_CONTENT_DIR value is not propagating to the get_stylesheet_uri() function (and similar others) used in the header. The following construct in the header
<link rel="stylesheet" href="<?php bloginfo('stylesheet_url'); ?>" type="text/css" media="screen" />
... attempts to load the new theme's stylesheet from the default wordpress template location - not one specified in WP_CONTENT_DIR
So far I've determined that function get_theme_root() does get the correct value - however it is not propagating to functions get_stylesheet_uri() and similar ones for pingback etc