The mustang is getting a 6.8 in a few years, the Windsor plant has confirmed Ford ordered them. No power numbers yet. The new LT1 camaro is a blast to drive.
If we do an apples to apples comparison and look at the newest Mustang platform versus the newest Camaro platform, I think the Camaro wins aesthetically by a long shot; the S550 looks like a Honda Prelude until you get into the high end versions (GT350/500).