If it's a big realease, it will probably be the new ipod. Not too much smoke with the realese of the 24" imac or even the mac pro. So a chip change in the MBP wouldn't be too big of deal.
"Analysts have speculated that Apple will use a September event to launch numerous product and service offerings, ranging from new iPod nano and video models to a 23-inch iMac, new iPod-inspired phone and a movie download service."
http://www.ilounge.com/index.php/new...eptember-12th/