Defensio is a spam comment blocker. Defensio boasts a few features lacking in Akismet, most notably the ability to sort your blog’s blocked comments by “spamminess”, according to Mark Hendrickson at TechCrunch. That got me interested enough to try the Defensio plugin at my WordPress test blog, but then realized that WordPlay doesn’t get enough spam comment to provide a test of Defensio.
Mark refered to “a few features lacking in Akismet,” and goes on to imply Defensio’s “open API that makes the blocker available for use with non-blogging applications” is one of them. But that feature is present in Akismet, and clearly described in the FAQ: The Akismet API can be adapted for almost any application with submitted content, including forums, wikis, and contact forms.