Apple has begun emailing select members of the press, inviting them to a special event in San Francisco on September 1. As it has been in the past, the event will be held at 10:00 a.m. Pacific Time at the Yerba Buena Center for the Arts Theater, and will be focused on the company’s iPod line, as indicated by the invitation’s image of an acoustic guitar with an Apple logo cut-out. Apple is widely expected to introduce updated iPods at the…