Finiteness of N=8 Supergravity?

Green, Russo and Vanhove have just posted a paper saying that N=8 supergravity has only logarithmic divergences and it could be UV finite. They use 11D supergravity and dualities inherited from M-theory. Lubos Motl has a long post on the subject with a good review on the loop results in supergravity. As he correctly points out, if N=8 supergravity is perturbatively renormalizable or even finite then we must include also the nonperturbative sector. He then claims that including the extended objects of the nonperturbative sector would inexorably lead do string/M-theory. A very nice argument !!!