While there are several modifications to the OpenID standard, one of them is crucial. In Google’s scheme endusers use their gmail address instead of a URL to identify themselves to accepting sites. I believe that this is a crucial step towards widespread consumer adoption. Many sites already use email addresses as the primary username, so this is something that will be very easy for consumers to get used to. Conversely, trying to change behavior and get folks to paste a URL into a username field has been the primary obstacle to consumer adoption of OpenID to date.
I agree — this will make OpenID much more palatable. As it stands now, there’s zero practical reason for anyone to use it on either end.