2
I have done this on my site. Three different groups each get their own news even though they all visit the same main page. You just need to set up the permissions accordingly. It takes a little foresight to establish appropriate groups, but once you have your userbase divided into their groups it's easy. Especially since you can add the same user to multiple groups if you wish.
Only admins post news on my site. I haven't looked into allowing users post news themselves. I'd imagine it wouldn't be a problem.
I do the same for my forums. Each group sees only that which they are supposed to.
In case it makes a difference, I use the 2.2.x version of Xoops.
...