FWIW I was looking this summer at a Rav4 and told that the one I wanted would have to be specifically ordered/built, as none were in my region. The salesman said 4-6 weeks from order to delivery.
I just placed a Toyota factory order this week through my company's fleet site for a 2011 P III as my new company car. The worst case delivery date is Jan 12 so I would assume the dealers would have them November?
Based on the latest info, with the large inventory of 2010's, production is delayed until November/Dec, with shipments arriving in the U.S. in January for 2011's.
My guess is initial production month November, with initial delivery Dec/Jan: http://priuschat.com/forums/gen-iii-2010-prius-main-forum/84158-my11-prius-not-until-dec-jan.html
On the prius facebook page, Toyota made a reply to someone now stating that they may see them in dealerships in December. BUT from my experience, that means for the west coast. It'll be right at the very very end of Dec. into January before the east coast begins to see em'...