I run a popular vbulletin forum, and reCaptcha definitely stopped working months ago. We switched over to Vbulletin's questions and answers and created our own custom questions, and that improved things significantly.
We also added the akismet check to the first one or two posts by a user, and that has helped catch a good bit of spam as well. So far we've only had one or two false positives, and their posts got approved within a day or two.
We've gone from deleting 5-10 spammers per day to less than five per week, and because of the akismet plugin, most of the time the spam never gets seen publicly.