The New York Times has a basic, easy-to-read comparison of the Canon HV10 and Sony HC3 digital high-def camcorders.
It outlines the image quality of Canon's offering, and compares the physical gyro-based image stabilisation of the Canon with Sony's digital equivalent. It also looks at connection options, and the similarly poor wide-angle shot on both cameras.
It's an easy read that as much sells the whole concept of starting to film in high-definition.

I was looking to get the HC3, but this review has swayed me more towards the Canon, especially since a lot of what I film is in low light (music gigs), and the small LED light on the front will help a bit too. I'll now have to wait until the canon's released in the US on the 30th Sept to see some real reviews (or until camcorderinfo do one of their thorough reviews!)