Yes - this is the main benefit to OpenID from a user standpoint. Unfortunately, right now, there is a "chicken and egg" problem. Users are not motivated to get an OpenID because relatively few services support it, and services are not motivated to support it because the conscious userbase is relatively small. "Conscious userbase" meaning those users that actually realize they HAVE an openID. I suspect there are many users that have an OpenID and don't even know it, or if they do, don't realize what it is or what it is useful for.
