As there's more and more real consideration for the "cloud" (something that means a lot of different things to different folks), I think you'll see more of the IT companies at shows like these. Not just Amazon, but others that have been around for a while, like Media Silo, Signiant, Aspera, and others.
The whole idea of trade shows is a throw back to the days when gear was super expensive and it was easier to move people to the gear. Now it makes almost no sense to go to a trade show apart from putting faces and real personalities to online names. I haven't been to one for ten years