Current rumors I've heard claim a Duratec 3.5 will be available for 2007 production, but will probably show up in Lincoln/Mercury or upscale Ford models before making to run-of-the-mill 500 models. Learn more at
http://www.myford500.com
I've seen a 500; think of it as a Ford knock-off of an Avalon. Personally, I think that's a good idea; Oldsmobile might have a future if they had simply copied the Avalon five years ago. When my in-laws (who have owned Oldsmobiles for years) bought an Avalon, my first impression was "Hmmm - A Toyota Oldsmobile!".
Interesting: Ford gets beat up for bland 500 styling. The Avalon is just a bland, but no one chastises Toyota. If Ford can keep quality up and prices reasonable, I think they'll have a winner on their hands, no matter what the auto press says.
As I mentioned earlier, think of the Fusion as more direct competition for Camry/Accord than the Taurus ever was. Again, if Ford does a decent job with quality and keeps a lid on price, I think they'll sell quickly. Please, Ford - offer a Fusion with three pedals!