Yeah! Alhamdullilah it's done!
Here how it works..
You basically have a button "Wikipage" in each group home page. When you click on that button you have a small window with a form, and when you submit your data, you will have something like "Bob created a new wiki page titled Foo Bar".
The cool thing is that this wikipage is global. It is possible for a user outside the group, say Alice, to edit the page. When she does so, the members of the group will see something like "Alice edited the wiki page titled Foo Bar".
The idea behind it is simple, keep all content global and make groups follow that content. Creating a wiki page from inside the group page means that this page should be followed by that group.
This is what has been done so far. We will certainly work on allowing users to annotate any content as to be followed by their desired groups. This will allow cross-group collaboration and interaction. For instance if Bob sees a good wiki page on the website that might be interesting for the rest of the group, he can make the group follow this page, so every action or development on that page will appear on the group page (this is quite simple to implement in fact).
So in the end we will have global content accessed and followed by different users and groups.
Best regards,
Amjad