I just want to mention something quickly.
There seems to be something buggy going on with my WordPress blogs (at least these are the only blogs manifesting this issue). If you have left a comment here you know what I am talking about. Unfortunately this bug seems to be having an impact on notifications of new comments and that means our response times to comments is a little slower because we actually need to log in to the backend to find the comments that you leave. The comments are, notwithstanding the error message you see when you comment, being posted. We’re just not being notified when you do so we apologise if it takes a little longer to respond to your comments. I am curious is anyone else has experienced similar strange issues after upgrading to WordPress 2.1?
It turns out these errors were due to a classic case of RTFM (read the frikkin’ manual). One of the things you have to do when upgrading from a previous version of WordPress to WordPress 2.1 is actually delete all the WordPress files in your directory and upload a fresh set of files (just make sure you backup the directory first and restore all your customisations in the WP-Content folder as well as your wp-config.php file too – don’t delete these or you will have a completely empty blog). The instructions are here. Follow them to the letter!