What makes red velvet cake, red velvet?

I believe these days it's just red food coloring, but as allans said above, it got it's name from the reddish color brought out from the cocoa powder. Wikipedia has a little history on it if you're interested-- http://en.wikipedia.org/wiki/Red_velvet_cake

My grandmothers recipe didn't use food coloring, just cocoa powder with boiling water added. Not bright red like some, more red/brown. Still delicious and one of my favorites to this day.

I might be wrong, but I believe the classic way is to use Beat Juice for color and flavor.

2-3 TB of cocoa powder and 2-3 teaspoons of red food coloring.