They said that they used a PC "in between" because they wanted to capture the data/process of how 2 or more 'Cubes communicate with each other over a LAN. Then they take that data and try to replicate it online. But I hope GameSpy is making the tunneling software for LAN games. I just want to play Double Dash online and I'm happy.
Well if MKDD does go online it will more then likely be through gamespy, who already has the program and power to do that with features like chartrooms, rankings, and player matching.