While working on a new site I discovered, that reCaptcha - which used to be a rock solid part of the CMS since Joomla 1.7 - stopped working. Spent couple of hours googling around and checking and double-checking settings, just to discover, that Google, in his infinite wisdom, has changed things again without notice. The problem affects all Joomla versions from 1.7.1 to 3.2.0.