I have just made live some major updates to our API rulesets for initial signups. Our API filters have proven EXTREEMLY effective (>96%) at detecting sploggers when they post and shutting them down. But you have noticed and we acknowledge that our rules are not so effective at detecting splogs at signup before they post, in fact splogs sometimes don't even make it to the suspicious queue. This is due in large part to the limited amount of information there is to analyze at signup, and splogger's ability to manipulate most of this to avoid detection.
Thanks to many suggestions from you members and lots of experience and sluthing with the data we've collected so far I was able to tweak our rulesets and add a few bells and whistles, and they should be live right now. What this means is that hopefully the API will be able to detect a much larger percentage of splogs right at signup, and at the very least mark them as suspicious!
As always, I welcome any suggestions and feedback on splog patterns, especially any large swings you see on your site, like a sudden jump in splogs getting past or false positives.
To be clear you DO NOT need to update your Anti-Splog plugin to take advantage of this as the changes are to our servers and all new signups will get this stricter treatment!
Also a 3.0 compatibility update for the actual plugin is ready to put up live when WP 3.0 is released. You will need to upgrade at the same time you do to WP 3.0, as this release (along with most others) will not be backwards compatible with 2.9.2.