I like buying new too. I don't mind taking the hit, it's just worth it to me to know everything that car has been through. It may cost me more in the long run, but I still like it.
as far as the 0% financing. I KNOW that's a tough choice, and to be REAL honest. The 2010's I think are still better than the 07 I have, and I think are still VERY competitive with the Camaro and Challenger. Car and Driver did a comparo a few months back.
If you're not hell bent on the more expensive 2011 and the 5.0 engine with 412 HP and better gas mileage through the use of a 6 speed tranny, then I would think the 2010 is STILL a good buy.
I may wait for the 2012 model, I'm hearing a BOSS 302 scheme is coming. I had 2 dream cars as a kid. A 67 Chevelle SS and a 70 BOSS 302 Mustang....I have one, and the chance to get a newer version of the second one is very tempting.
a THIRD option would be to find a slightly USED 08 or 09 Shelby Cobra Mustang. I know where a 6000 mile 08 model is for about 40K. I keep hoping they will sell it so I don't have to keep looking at it on the internet! lol