I think the paper is (perhaps a slightly different version of) this one: http://arxiv.org/abs/1212.1739 in which the researchers found evidence that favours the hypothesis "the D-Wave device is doing quantum annealing" over the hypothesis "the D-Wave device is doing classical simulated annealing".
That's very interesting scientifically (though it's not clear to me how far they've ruled out other basically-classical processes) but it's important to notice what it isn't.
It isn't evidence that D-Wave's device can perform the operations usually denoted by the phrase "quantum computing". (So far as I know, no one thinks it can.) So, e.g., there is no known way to use it to break RSA encryption, no matter how well it does the things it does.
It isn't evidence that there is any problem D-Wave's device can actually solve faster than a classical computer.
It isn't evidence that there is any useful problem D-Wave's device can actually solve faster than a classical computer.
See http://www.archduke.org/stuff/d-wave-comment-on-comparison-w... for some comparisons between the published performance figures for D-Wave's device and simple software running on (one core of) an ordinary laptop. The laptop comes up faster every time, even solving the exact problem D-Wave's device is designed to solve.
That doesn't rule out the possibility that there may be other instances of that problem that D-Wave's device solves much faster than anything you can do on a laptop (but no one seems to have found any) nor the possibility that some future version of D-Wave's device may be much better because it scales better (though Alex Selby's figures aren't particularly encouraging on that score). But claims that D-Wave, now, have a useful quantum computer don't look very plausible.