Server should provide the identity URL

[Omar Syed]

Looks to me like there is no need for the EndUser to tell the Consumer
what their identity URL is. In the end what the Consumer
really does is check to see if the EndUser is logged into the account
they have with an OpenID Server site (via the User-Agent). Provided
that the EndUser is logged in and has notified the Server that they
trust the Consumer site, the Server can give the Consumer the 
identity URL of the EndUser from where additional information can
be accessed (such as a public FOAF document). The EndUser only
needs to tell the Consumer the "simple" URL of their OpenID Server.

In the Overview section of the Specs page:
  http://openid.net/specs.bml
if Bob wants to use livejournal.com as his OpenID Server then
Bob should only have to enter: 
  livejournal.com
in the text box of the Consumer site. The front page of a site
that is an OpenID Server (livejournal.com in this example) 
should provide the LINK tag which defines "openid.server".
The Consumer will then get Bob's identity URL from the OpenID
Server. 

But how will the OpenID Server know what Bob's identity
URL is? Well Bob already needs to maintain an account with the
Server and tell the Server which Consumers he trusts. Bob can
also provide his identity URL in this account.

What if Bob wants to change his OpenID Server from livejournal.com
to deadjournal.com. It's just as simple as before. Bob enters his
identity URL (http://bob.com/) in the new account he opened with
deadjournal.com and begins entering:
  deadjournal.com
in the text box of Consumer sites.

This avoids the problem of EndUsers needing to tell the Consumer
sites their identity URL which are typically specifed down to the
level of a username (not a good thing). This also avoids the
whole issue of wanting to enter an email address like URL for 
the identity URL.

I won't go into the details right now, but doing it this way will
also allow for more flexibility and enhancements in the future if the
scope of this project increases. Right now you are only looking at
this project to satisfy the need of simple identification for 
adding comments to a blog or forum. However, if this project becomes
popular and catches on people will want to apply it for more 
broader use.

This is a critical design issue and I think you still have time to
change it if you want to. Later on it will be hard to change.

Omar