I am working on a new plugin called
Fast Secure reCAPTCHA Anti-Spam
it does the comments, login, registration, lost password, etc.
Similar to my SI Captcha Anti-Spam, but with reCAPTCHA and a total code rewrite.
It will be compatible with the reCAPTCHA you can enable on Fast Secure Contact Form. I have it working already. Just making final features design before release.
Most reCAPTCHA plugins are not compatible with each other because of javascript onload conflicts but I know how to make my plugins compatible with each other.
Until then you can deactivate the reCAPTCHA in the form Security tab and enable Secure Image CAPTCHA so the other reCAPTCHA plugin still works as a temporary measure until my other plugins is released.
Mike