The owner of several gossip web sites including Silicon Valley’s valleywag.com, Nick Denton, has posted this memo saying that he’s going to sell two of his 15 Web sites and reshuffle his staff due to economic concerns including a fear advertising revenues will decline. “A change in the advertising industry’s conventional wisdom, cutbacks by the studios: it wouldn’t take much to prick the current exuberance. Better to sober up now, before the end of the party,” Denton wrote. Sounds like things we’ve heard from newspaper executives in the past.