For a moment last night (about two hours), Googles reCAPTCHAs became unavailable. I thought at first it was a botched update I made, but I found a newly created post on the reCAPTCHA Google Group page describing similar problems to me.
After waiting an hour, I decided to disable the CAPTCHAs on the forms to at least enable their functionality again. I didn’t want to open the forms to abuse too easily though and wrote a simple mathematics based question and answer anti-spam check. It can be broken with a bit of effort, but that is why the Google reCAPTCHA is the first choice.
On completing the changes to the forms (about 3 hours after I first noticed the CAPTCHAs being broken) I then noticed that the CAPTCHAs were back online, so I re-enabled the original anti spam measures and left my code on the shelf. So, the code isn’t in the wild yet, but it’s there ready just in case.