If you’re using the buddypress theme you could add as left-coloumn widget, the activities’ widget. Simpler than that! 
Maybe I do not quite get, what you mean…
I don’t need the sitewide (global) activity, but just to show the activity of my friends (–>the friends activity-stream of the logged in user) in a different place than the profile. Where is the piece of code I would need to do that?
I think andy hasn’t developed yet this part of code :S
I have this functionality working on http://sunysb.net
I had to modify 2 files in bp-activity.
bp-activity-classes.php – I had to make the output of get_activity_for_friends formatted like the other two, I don’t know why it wasn’t already formatted.
bp-activity-widgets.php – I basically copied the code for the sitewide widget and adapted it for the friend feed.
I was also working on the friend rss feed because it doesn’t work at all. You can see that when you go to My Account>Activity>My Friends and click on the RSS feed. Even if you have activity on the page, it won’t show up in the rss feed. I can talk more about where that bug is hiding if anyone is interested.
I would be happy to post my changes somewhere, but unfortunately I don’t know how to abstract this into its own plugin. I think this should probably be part of the default activity plugin anyway.
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