You can have a copyright on a compilation of works that are themselves not copyrightable. For instance, a recipe is not copyrightable, but a collection of recipes is, even without additional commentary.

You can google "compilation copyright", or see http://www.pddoc.com/copyright/compilation.htm for example (second hit). Note that it gives you much more limited protection than a traditional copyright, in that you only have a copyright on the collection, it does not give you a copyright over the parts. However, it sounds like the potential infringement in question is for the entire collection.

Whether or not Fluther could claim a compilation copyright would probably be a matter for lawyers to work out in court, by which I mean, it's an awfully close call. The courts have interpreted the word "creative" fairly liberally, but I could see a court saying that simply passing through the posts of other people with no editorial oversight and collecting them together does not itself meet a standard for creativity. Who knows, though? The list of things courts have judged to not meet the creativity criterion is quite short.

That might be Fluther's best claim. But it hardly seems Fluther is adding much originality (via "selection, coordination, or arrangement") in the raw log of questions. (Perhaps, in the editing and rating of answers -- but Mahalo isn't taking the answers.)

And Fluther's very complaint against Mahalo -- the removal of Fluther's full context -- suggests Mahalo isn't infringing the aspects showing originality at all.

I'm not a lawyer, but I believe if you scraped all the Q&A sites to make a massive database of questions, that would in fact get you in a lot of trouble.

Honestly, I don't know if we have a case here, but I'm curious to hear what people think.

All the Q&A sites want Google traffic. Google has scraped them all, and thus inside Google's index is a "massive database of questions". Excerpts from this massive database are used by Google to improve its products, and excerpts are often displayed as part of their cached pages or results-page snippets.

Is Google in "a lot of trouble" for their behavior? Should they be?

If they made it seem like the page was written by google, then yes, they would be.

Sure. But whatever Mahalo's done, they haven't made it seem like they wrote the questions themselves. The visual design attributes the questions to the 'fluther' Twitter account (and link to the exact origin Tweet).

Are you angry they're making questions by your users seem like they were written by Fluther itself? That seems a legitimate concern, but your own Twitter stream similarly blurs question authorship.

Are you angry that they synthesized a 'fluther' account on Mahalo and thus made it look a little like you're endorsing Mahalo with your participation? That's what I would be most angry about, if my question-tweets were showing up, under my unique username, at a site I'd never opted into. But one remedy for that concern might then be to remove attribution -- making the questions from 'an unnamed Twitter user'.

But that doesn't apply here, as Mahalo is linking to the Fluther twitter account.