Your app could refilter what the API returns.

Please don't use URL shortening services. They are completely unnecessary. This is not Twitter.

I like the idea of an authorized set of official graphics with unrestricted (or nearly so) use.

@George: No, the userxxx names are for unregistered users. @Jonathan: The empty display name is for registered users, based on their OpenID, who have not entered a display name such as the one in your second question (as pointed out by S.Mark). It's related to Jeff's answer to the question I linked to above.