Currently, Wikipedia is participating in a blackout and going to any content on their site produces a result like this (cropped slightly to dissociate the example from the message behind the example):
However, if I look at the source, I can see the full source of any article (this is the content for the entry on G.I. Joe, I've highlighted elements in the source to indicate things that I would expect to see under normal circumstances):
Now, I can't say what Googlebot is seeing (I would hope the same content is being served up to Googlebot, as doing otherwise smacks of what Experts Exchange used to do), but that aside this all seems very grey-hat, even if it is only temporary.
So the question is, even if it is only for a short amount of time (in this case, a day) is what kind of SEO practice is it considered to deliver content in this way. Black, white or grey? And if grey, how grey?