In v7, you can control what you get a notification for (stage change, discussion,...) but you cannot control what other followers get a notification for. Each user decides what he follows. What you could do is change the default so that if you add other people as followers, they will get notifications for everything. That's a custom development.

Now, I'm using the word notification because it is going to display a notification in the Messaging App and whether or not it will also send an email about the same is up to the user. A user can request to receive an email of every single notification he receives in OpenERP through his Preferences menu in the top right corner.

Rumor says that v8 would allow to choose what to subscribe someone you add as a follower for. Let's see.