"What Matters" is nice, but it's usually one click away. I'd like to get an additional status bar at the bottom of the web page which refreshes every minute. To limit the space used one may use overlay technologies or something like this.
It should show new What Matters activity like:
XXX is now following you
XXX assigned you a task task-description
XXX sent you a private message
XXX mentioned you in YYY
And maybe even more information like
XXX (friend) is now online / offline
50 users and 5 friends are currently online
The underlined texts should be links to the relevant user or content.