Improvement on privacy by tagging tabs

Hello,

The problem:
Currently, Google+ gains a lot of momentum, but, in my eyes, has one major drawback: If you log in to Google(+, Mail, whatever) on Opera, potentially all your searches will be associated with said Google account. Obviously, sometimes you don’t want this to happen: While one can trust the local browser, trust in external websites is much lower. Due to HTTPS-encryption, it isn’t even possible to ‘clean’ search requests with external tools, such as privoxy. A possible solution is another browser dedicated to Google+, but this is quite clumsy. A similiar problem exists with facebook’s ‘Like’-buttons, however, it is much easier to block these by using Privoxy on non-HTTPS sites and/or blocking the appropriate URIs locally.

The idea:
Introduce ‘tags’ for tabs. These tags are inherited to children, such as that if tab A is tagged as ‘tags:A’ and I open a new link from that tab, the new tab also has ‘tags:A’. If any of these two tabs receives a cookie or some similiar means of identification, it is also tagged as ‘tags:A’ and can only be accessed by sites that also run in a tab with ‘tags:A’. At the same time, a tagged tab cannot access any non-tagged cookies. Obviously, it would be nice if the tags a tab currently has were somehow indicated in the tab bar, maybe with colourful icons or something similiar.

tl;dr:
Run multiple browsers within a window by tagging tabs so that they can only access information owned by their respective tag-group.