Google currently, directly competes with Time Warner, but I am not sure about Comcast (not sure all the boundaries) locally/regionally. Also Google does have a business relationship with Comcast (its search provider). The last thing that wasn't search, that I knew Yahoo competed against, was Ebay, back when Yahoo had an auction section.
I wish I had seen what Steve saw. I find that argument interested, since just a few years ago, Comcast and Time Warner swapped some service area's.