I’ve done some e-mailing on the toyota-prius and Prius-2G Yahoo! Groups, and there appear to be a number of people who have first-generation Priuses with easily twice that offered mileage (one person cited 180,000 miles, a bit under twice the number of miles on the eBay car described below. Here’s the incredible part — he claims to still be on his original set of brakes!).
This doesn’t really settle the question, since with each new model year, we get slightly different reactions. I would anticipate that the second-generation Priuses (2004-5 model years) will fare just as well, if not far better.