Yoav, If you could just add a role to a site member so that you can assign it when you approve the member, that would work for me.
Also related but not exactly the same issue, I was wondering if it is possible to load a list of names and email addresses as “preapproved” this would be helpful for many organizations. I could load all my organization members into site members, then when they create a logon using the same email address then it automatically approved.