2011/2/5 David Gerard dgerard@gmail.com
(It's a real pity reCaptcha is third-party and proprietary.)
Well, we it.source fellow are writing our communication about (it will be published into wikisource-l), but a brief mention to good news is mandatory here.
We have a simple script that extracts word images, corresponding to doubtful OCR interpretation, from any djvu file with a text layer; scripts to upload into djvu layer again fixed words are simple too.
We posted first communication into John Vandenberg en.source user page, and a wikicaptcha is now something possible. See John's lalk here: http://en.wikisource.org/wiki/User_talk:John_Vandenberg#reCAPTCHA_for_source
Alex brollo