Kudos to Ben and the rest of the Captcha team.

Today I downloaded the binaries for reCaptcha.NET for a web page that I was setting up and it worked out of the box. No recompiles necessary:

• Drop the Recaptcha.dll in the bin directory of the ASP.NET app.
• Get your public/private key.
• Insert this in your page:

  		<recaptcha:RecaptchaControl
                          ID="recaptcha"
                          runat="server"
                          Theme="red"
                          PublicKey="YourKey"            
                          PrivateKey="YourOtherKey"/>
  		

• Hit refresh. Ta da!