This was a relatively private Jenny Lewis show, that was put on by her record label. The guests I've seen were either her friends (like Vanessa Bayer, Reggie Watts, Feist, etc.) or corporate people (from Warner, Fender, etc.).
The night was written up in Billboard. Jenny performed five songs with a makeshift band that included Jim Keltner, Benmont Tench of the Heartbreakers, Jason Falkner, and Don Was. Gus Seyffert, who was in Beck's Morning Phase band, was also there. None of these musicians are her normal touring band, but most did appear on her latest record (as Beck did).
Fred Armisen was the host.
Beck was on a week-long break of his tour, and showed up and sang backup on "Rabbit Hole" and "Little White Dove," both songs he produced on Lewis' most recent record. He apparently told the crowd he had just stepped off the plane.
She played "Heads Gonna Roll," "Wasted Youth," "Red Bull & Hennessy," "Little White Dove," and "Rabbit Hole." I'll only include the latter two below, because they're the ones Beck sang back-up on.