This news can be interpreted according to your affinity for Groupon. If you're skeptical, this is yet another strike against the model, the canary in the coal mine. If you're optimistic about Groupon, this is a win, a step toward answering the claim that there's no means for them to outcompete all of the clones.
It will be interesting to see if any more details come out, and if it's possible at all to establish which interpretation is closer to the truth.
Can I throw in "Clearly, Facebook is in the end-stages of negotiation to acquire Groupon!"? I mean, as long as we're all staring at tea leaves, let's have some fun.
Actually, a partnership with a current deals site I think would be a great idea. Facebook can bring in an audience for free but not have to worry about finding deals.
I look at it the other way round: either it's an indication Facebook believes that check-in deals will prove vastly more lucrative than what is essentially a digital equivalent of untargeted coupons you cut out of magazines, or a scathing indictment of Facebook's failure to generate non-trivial revenue from this type of promotion despite arguably the best platform in the world for running it.
It will be interesting to see if any more details come out, and if it's possible at all to establish which interpretation is closer to the truth.