All Things D claims that the Oct. 4th Apple event will be held in Cupertino. Swisher goes on to say that the new phone would be "quite different" and would hit the shelves around the 15th. She ends with the caveat that Apple likes surprises and anything could happen.
This site is a part of the Wall Street Journal "family" and the reporters have real sources rather than just passing on rumors from other sites. Their recent track record is pretty good. Just note the caveat they end with.
? Oct. 4th event in Cupertino
? iPhone "quite different" (assume that means physical appearance)
? availability ~a week later