We ordered ours mid-October of 2004, and were told that it would be approximately 2 months. We were pleasantly surprised in mid-November of 2004 to be told that our Prius had arrived and was waiting for us.
A week ago left a $1000 deposit and was told 2-3 months. After reading somewhere here about calling 45 dealers because everyone gets on multiple lists, I emailed a bunch of dealers and called too. Started getting some responses, but emailed a guy yesteday, who called me back within 2 minutes and said he had a Pkg 8 in silver. Did I want it. Well, not really, but after hearing horror stories about waiting forever, and here was one within a week, we decided to take it. It is currently sitting in my driveway... cool.
Bought mine off the lot 5 hours after the salesman posted an ad for it on craigslist. Was looking for a used one for several months, but couldn't find one for the price and in the color (Driftwood Pearl) or condition I wanted, so when I saw the ad for a 2006 in my color of choice, I just jumped on it. I wanted Package 3 but it had a Package 6 in it, but bought it anyway despite the additional $3k. There are Prius(es) consistently offered on the lots these days in the SF Bay Area, so you shouldn't have to wait unless you're fussy about the color and/or the option package.