I reviewed a powerpoint presentation on my iPod Touch/iPhone using Citrix Receiver. The test generated 1.9M bytes network traffic, which is 14% of the 14M bytes file size.
Bandwidth consumption varies depending on applications and usage pattern. This is one data point. I would encourage you to do your own test yourself.
More details about my test and methodology including the power point file can be found at Citrix Developer Network Mobility Section