Integrates Picatcha image-identification CAPTCHA - anti-spam solution with WordPress including comment and registration.
Moderation Emails: Picatcha(TM) marks comments from users who do not pass the Picatcha(TM) test as spam, so they will still appear in the spam category of the comments section.
Picatcha(TM) cannot do anything about pingback and trackbacks. Those can be disabled in Options > Discussion > Allow notification from other Weblogs (Pingbacks and trackbacks).
Where can I get the public/private keys? Keys are available from PICATCHA's website - http://www.picatcha.com - once you register, you will get the keys to start using Picatcha(TM)
How does Picatcha(TM) compare to other CAPTCHA systems such as reCAPTCHA? Picatcha(TM) uses image recognition, which is easy for humans to do, but still very difficult for machines. With text based CAPTCHA systems, computers can undo the image transformations which make the text difficult to read, and then match the shapes of characters with Optical Character Recognition. Image recognition is still more difficult to do, especially when noise or other transformations happen on the image.