Yesterday (Thu, 6/17/10) Toyota announced they have re-started construction of their new plant near Tupelo, MS, originally planned to produce the Prius. Unfortunately, Toyota has changed plans and announced that this plant will now build the Corolla line with the first cars due off the line in late fall 2011. I guess North America needs another oil crisis (other than the BP disaster in the Gulf) to raise gasoline prices so more Priuses will be sold. The local Toyota dealer in Gulfport, MS had 5 Priuses on the lot when I was in last month. They're now offering purchasing and leasing discounts in their TV ads.
The Corolla is also much cheaper than the Prius. Sales probably reflect people's desire to conserve the money they have.