Virtual registry profiles, virtual desktop shell

Is it possible to obtain some kind of shell that will load its local determined registry,so all apps started after, will R/W that transported virtual (in the moment real) registry.

Usage will be as virtual desktops or virtual profiles.
In that case,non portable apps will be part of one of virtual profile desktops...

Some backups of reg hives is needed,but is it possible with nowadays development of portableapps knowledge base to do this...(i hate MS declaration of profiles,registry nightmare)