gonna be real interesting to see if Kendrick has a verse on MML2. Usually Em doesn't seem to kick it with people with young rappers; that Forever song was one of the first times I remember him doing a big collab since The Blueprint.
Ignoring guys like Obie Trice, G-Unit, and Hush (apparently a friend), he's done songs with Cashis, Bobby Creekwater, Trick Trick, The Game, did a chorus with some dude named Strike, BOB, Akon, Yelawolf, chorus on a Jeezy/Gibbs song, Lil Wayne (not young/new though), Nicki Minaj.