Showing different/shared posts on multi domains by TAGs

Hi all,

I’m facing a problem which cannot be solved by multisite alone. Let’s assume I have:

http://www.example.no
http://www.example.se

I want these two domains to share the same WordPress installation. However, when you go to each domain, you will see a list of different/shared posts (identified by tags). For example:

Post A (tag NO)
Post B (tag SE)
Post C (tag ALL)

Hence, when you go to http://www.example.no, you will see posts A and C only, and so on.
I believe that this approach would be very useful for everyone, since once we have a country-specific domain filter, the rest that we have to do is just tag the posts. But I’m not very sure about the implementation. I’m grateful for any of your helps to solve this problem.

PS: I’m not using multisite at the moment, I only use Multiple Domains with Analytics plugin to maintain the url (ie. when u go to http://www.example.no/abc and go back, the url still remains as http://www.example.no)