I wish to keep some stack exchange account separated from others, having (and using) more than one OpenId is a pain. However I already have more than one email address that I use to control gravatars etc.
Therefore please associate accounts based on confirmed email address.
If the account does not have a confirmed email address then the opened could be used as now. For most users there will be no change, as the “starting” email address is provided by the OpenId provider most of the time.