Arrived about 10 minutes into her set--big mistake.  The Sahara tent was exploding with people.  Tried to weasel our way in the side but gave up and managed a spot near the back of the tent.  This is not my ideal place to stand, but it really didn't matter--front, back, sides--everyone was into it and the sound was great.  Despite M.I.A. spending 15+ minutes yelling, "Turn off the lights!!!  Turn off the lights!!", I still think this was an incredible set.  Her performance of XR2 was the highlight of the weekend for me--by far the most energy I felt in the crowd during the entire festival.