Ben Pfeiffer spotted possibly the first OneBox Q&A adult spam in the Google results, that I have personally seen. Ben posted the details in a Search Engine Watch Forums thread, describing the result set one gets for a search on dating services sites. Try it, and at this moment in time, you will get the following result.
The link leads here and the more sources link leads here, but here is a screen capture of the more sources just in case it gets pulled.
It also works for religious dating sites. Looking at the site itself, one may consider them to be pushing the envelop on search spam.
Now the question in many SEOs minds, is how they broke the algorithm to get their site included?
That is the the 2nd set on OneBox style spam we have located. The first was package tracking spam but those results were found in the organic listings and not in the OneBox area.
I notified Google about this yesterday afternoon, I have yet to receive a response on the matter.
Forum discussion at Search Engine Watch Forums.