According to this French website quoting the Apple communication department, the iMac should be updated by the end of 2012, maybe fall. No redesign announced. http://www.menly.fr/high-tech/informatique-et-gps/93667-sortie-imac-mac-pro-2013-keynote-tim-cook/
No chit Sherlock. Did you actually think Apple's flagship computer is going to go almost two years without an update? They are simply waiting to release it with 10.8, all the hardware has been available for months and that is the only excuse they have had to delay it since March.
That just seems to be recycling the Pogue article from the New York Times, and the later article from Forbes that clarified what Pogue said.
Not sure how this guy managed to get "October or November" out of the Apple PR quote that didn't mention the iMac at all.