First off, you cannot plug directly into the iPad. Sure there is the Camera USB/SD card reader kit, but that doesn't allow other devices such a phones to connect.
I have a PPC 6800, with Bell/Aliant, and I can take me incoming connection and broadcast it as a WiFi hotSpot, which I use my iPod Touch with, so I dont see any issues with the iPad, but the USB idea is not gonna fly.