Time once again for Allen & Co.'s media fest in Sun Valley, Idaho, where IAC Chairman Barry Diller apparently expressed pessimism about Twitter's prospects for making money. I say "apparently" because the event was closed to the working press, and reporters were stuck confirming comments from New Yorker writer Ken Auletta, who moderated the event. Liberty Media Chairman John Malone seemed to be in agreement with Diller, saying that he didn't think an advertising model made sense on Twitter. But he didn't rule out a subscription model. Evan Williams, CEO of Twitter, was in the audience, but didn't say anything. (Digits)