The documentation says that in order for binding to work correctly in ASP.NET applications, the BOs need to be saved

in the ApplicationBasePage and maintained in the session and ofcource they will be maintained in the view state by the controls. As far as i know, lesson 1 in web development is session should be kept to minimum.

Any thoughts?

Yes, they will be held within the view state of the controls.  We are planning to incorporate an attribute that at will allow you to specify whether the business objects themselves are persisted within session variables and additionally allow you to specify the name of the session variable where it will be stored. 

But for now, all of the business objects are stored within the session variables.

So wouldnt this affect scalability? and why not remove them from the view state since we will be re-binding everytime from the session?

Yes, we can remove them from the view state through another attribute or remove them from the view state if they are stored in a session variable...