Actually, before slapping the cuffs on Apple's engineers and hauling them away to jail, it may be beneficial to look at this page with a few things in mind...
http://support.apple.com/kb/HT1085
I shoot Canon and use Aperture in my studio. I have been wanting to go up to the 5DII, as well as replace my aging 20D with a 50D. But will hold off a bit longer since neither of these cameras can tether to Aperture. Why? Most of the blame should be hefted toward Canon's corner.
Before the Mark III, Canon used a standard tethering protocol for their cameras. Since then, all the Canons coming out have switched to a proprietary tethering protocol, which can only be used with their software.
As you can see from the list of cameras above, all the Nikons work with Aperture.
Until Apple reverse engineers the Canon software (doubtful), Canon goes back to the industry standard protocol (doubtful) or Canon gives Apple access to their code - it is more than likely Canon cameras will not be tethered to Aperture.
So, I will stick with my 5D and keep my tethering abilities a bit longer.