Right after the release of WordPress 2.9, some issues arosed because of a last-minute addition to the core of WordPress. As a result of this: RSS widgets are completely broken on servers that are missing both of iconv and multi-byte string functions; The curl transport is broken on some servers with an outdated library. This breaks the WP cron, and with it future posting, pings, etc. If you have upgraded your sites to 2.9 and are experiencing any of these issues, the fix should be a matter of uploading these three patched files to your site(s). WordPress 2.9.1 is most likely around the corner. Meanwhile, you can download the patch files here or from trac which’s already a part of 2.9.1.