Yes, this is the same for us :)
We are planning to have this feature for the official release. We call it Browse and Edit feature.
Users that can perform browse and edit, are users that can actually change a content item from the back-end too. Their sessions will be counted in the concurrent users pool.
We haven't finished the implementation yet, but when a user should edit the page either from the live site, or from the administration, the page should be locked for other users.
Unfortunately we cannot answer to these questions now. They are helping us to clarify how the feature should work too. Therefore we are giving you 600 Telerik points.
I hope that we could discuss them again soon!