Some one want to give a run down of it for me? I keep having to say I don't know it when I am at pickups. Plus this forum could use some action.

If you envision the vertical offense like an inverted T, the horizontal offence takes the long part of the "t" and turns it 90 degrees. Instead of having cutting options to the left and right of the stack, each of the receivers has their own lane (to begin with). It's like four one-person stacks. This offense really requires the receivers to work together to create space for one another.

http://www.ultimatehandbook.com/uh/strategy_horizontal.html