Yes, that's real. Not a fancy edit.
Jeffrey Combs guest stars as “H.P. Hatecraft” and Harlan Ellison presumably plays himself in a recent episode of Cartoon Network’s Scooby-Doo! Mystery Incorporated in which the gang crosses paths with Cthulhu.
Between this and the three part South Park guest staring Cthulhu, I've got to say that 2010 has been a banner year for the Elder God. REPENT YOUR GOOD DEEDS AND TAKE CTHULHU INTO YOUR HEART AS THE TRUE GOD!