A very useful addin if you’re using WordPress for your blog. Add it to your plugins, turn it on, and it does the work. A few options can be set in the script to control whether you get notification emails, and to define some explicit regex values.
The other filters are read from the WordPress options page under Discussion (for 1.2.1).
Kitten’s Project Blog – Kitten%u2019s Spaminator
According to comments I’ve read, this functionality has been incorporated into WordPress 1.3, so you won’t explicitly need this plugin when you upgrade.