We told you earlier this week that the new Mos Def album, The Ecstatic, was the business. Hopefully you've already gone out and copped it. If not, and you should somehow need a bit more convincing as to its hotness (shame on you!), the Mighty Mos has been appearing everywhere (even here) performing cuts from the disc. His latest guesting gig was last night on Late Night with Jimmy Fallon, with The Roots riding shotgun on "Casa Bey." They ripped it! Clearly, this should be all the nudging you need. But wait, there's more. In case you missed it, check after the bounce for another Def appearance, this time on Late Night with David Letterman Monday with an electrifying rendition of "Quiet Dog." Yup, Mos Def is back and Hip Hop is alive and well.