Joomla! 2.5, the new long-term Joomla! version, will be released at the end of january. One of the new features affecting ALFContact is built-in captcha support by means of a new plugin type. Upon release at least support for reCaptcha will be included.
ALFContact v2.0 runs fine on J!2.5, however work has already started on ALFContact v2.5 to make full use of the built-in captcha support of J!2.5. Expect a release shortly after J!2.5.