If the average user uses, say, 1GB/month without tethering then Sprint can say they are offering unlimited data even though there expectation is it will average about 1GB. If the average user that tethers uses, say 5GB/month then Sprint will have seen there cost to provide service increase substantially so they expect additional compensation. If you, through tethering, were to constantly eat 100GB+/month you can bet Sprint will find a way to limit you even though you paid for unlimited data.
Sprint has given us several options for the data. When you get an Evo they automatically charge you $10/month more BECAUSE they expect you will use more data. They also have a $30/month wifi tether fee also to cover the additional data use. So, if you do not pay the $30/month fee but, through rooting, and you do in fact use wifi tethering to download many hours of midget tranny gangbang porn, there's every reason to believe you will be using more data than without wifi tethering.
Sprint has offered unlimited data for the basic service but the expectation is you will use, on average, only so much data unless you add wifi tethering. There are more than a few people that have gone from about 200MB/month to over 20GB/month with tethering -- I would suggest a 100X increase is something the carrier would care about. And, as I mentioned before, if I was stuck on the same cell with others downloading huge binaries, you can bet my service will be more likely to suck.
I think Sprint made a mistake by claiming "unlimited data" because that allows guys like you to conclude you can download as much as you want.
Now, I never said that free software was causing piracy. This thread was/is about app developers and whether or not they will move to Android as completely as they have the iPhone. I pointed out that there is a much lower percentage of paid Android apps and that many of them are junk -- no big revelation there... My point was that the Android community was much less inclined to pay for things so getting developers to spend 100's and 1000's of hours to develop and maintain an app that pays them nothing just aint going to fly in the long run. The mindset, the ethic, of expecting to take what you want without paying is pervasive today and is higher among the Android community than the iPhoners.
Brian