You can see a bit of Rob behind Kristen (and just his shoes in the last two pictures)
According to sightings (here), Rob and Kristen were with friends and Katy Perry on Sunday night (picture of Kristen with Katy, no Rob (here)
More details from the night:
Drawing an end to what was quite the weekend, Robert Pattinson and Kristen Stewart were spotted trekking through the crowds at the 2012 Coachella Valeey Music & Arts Festival in Indio, California on Sunday night (April 22).
Joined by a few friends, the "Breaking Dawn" co-stars were side-by-side at the Empire Polo Club venue, but quickly split apart from one another upon a paparazzo's arrival. (Source)
Rob and Kristen were also spotted at Coachella on Saturday night (April 21), but no pictures. Details here and here.
Thanks to Pattinsonlife & Kstewartfans for the HQ pictures from April 22 :)