False. You can't access your console friends list from every game.
The XMB friends list can be accessed by games. The best example is probably Ridge Racer 7, which shows you which friends are playing right now, and allows you to invite people from your friend's list whether in-game or not.
Blast Factor allows you to compare your score with people on your buddy list.
Its not entirely clear why all games aren't using the integrated list if the libraries are available to developers. Especially a game like Motorstorm, which is a first party game coming out a few months since launch. Evolution studios should really explain why they chose not to use it.
Either way, this is a "problem" that seems to have been solved on Sony's end (since launch), and the question is why developers aren't adopting it.