I just tested by re registering.
You have Image Verification at the beginning and
captcha at the end.

BUT: I was able to break through with the wrong image at the beginning with the image verification!
So maybe having a slow connection (that I have now) in connection with the back function of the browser and tipping on the same location of the picture every time may break your beginning verification.
Afair it said "Homer Simpson" I selected the wrong image, got the error message, took the back button (newest firefox) clicked on the same location (rose afair), the text still said "Homer Simpson" and suddenly I was at the registering page.

I'd check this if I were you.

Here's the list so far today:
[...]

Thanks. The new plug-in actually broke this one. I temporarily disabled it for the mean time and see if the new plugin is enough to stop the spammers. As of the moment, it looks like it's doing its job nicely.

Yes. They create email addresses from free services and they have automated the process of clicking the link on the verification email that they get.

Ok, so I guess that's where the bar needs to be raised. Is it possible to add some sort of turing test on the verification page?