John Brockman at his “Edge” web-site has put up an exchange between Smolin and Susskind about the “multiverse” and the anthropic principle. This includes the page and a half paper by Susskind that was rejected by the arXiv. Susskind seems quite willing to give up the idea that a physical theory should be falsifiable, so his response to Smolin’s argument that his use of the anthropic principle is not falsifiable is basically “Yeah, and so what?”.
To Smolin’s claim that non-falsifiable theories aren’t really science, Susskind answers by listing several prominent physicists (Weinberg, Polchinski, Linde, Rees), their titles, affiliations and prizes they have won. He then announces that since these prominent people agree with him and think the anthropic principle is science, Smolin should just shut up. I don’t know about other people, but one reason I went into physics was that it was supposed to be a subject where issues could be decided by rational argumentation, not appeals to authority. That doesn’t seem to be the case anymore.