Update: Apparently this isn't anything 'new' as PS3 online users are also reporting Army of Two, Burnout Paradise, and Rainbow Six Vegas 2 have an In-Game Friends List as well as Resistance for well over a year now.
Watchful reader StevieK08 has alerted us to the fact that the new Haze Demo has an in games friend list. To see it, get to the main menu, hit triangle once, triangle a second time, and voila!, up pops the friends list.
We have not had a chance to verify but Steve attached a screen shot that appears to confirm his story. If you have the demo, please give it a try and let us know. Thanks!