I recently implemented OpenID for a game I'm making (Google only at this time), and I'm using lightopenid. I'm asking for minimal information back from the user (on purpose), and when they successfully authenticate, I'm passed back a long URL that looks like this https://www.google.com/accounts/o8/ud
(I think that's pretty close to what it looks like, I don't have access to the database right now) with a bunch of random characters after it. I'm using this URL as the document ID in my database for fast retrieval on log in.
I'm getting to the point where I'd like to add player profiles on the site, but to do that, I'd need to publicly expose this long URL to other players.
My question is, is the URL I get back from Google safe to show other users, or do I need to find another field to expose to the user?