They are negotiating a storyline competition where we have WWE wrestlers fight in the octagon against UFC fighters, while UFC fighters cross over to wrestle in a WWE ring against WWE wrestlers. We'll have Undertaker vs. Junior Dos Santos, Anderson Silva vs. Rey Mysterio, and Kimbo vs. John Cena in the octagon. And we'll have Lesnar, Machida, and Coleman in a WWE ring against some "wrestlers."
But seriously, I think it has something to do with Shane McMahon leaving WWE later this year to pursue other ventures. I am sure he walked into the UFC office and asked, "Can I have a job." DW said "F*** F*** F*** F*** F*** F****.......Sure, you start Monday."