The unlimited data that Sprint gives you is not supposed to be for tethering. If you want the tethering app on Android to work, you need to pay Sprint a monthly fee of $30 a month. [1]
I have a hunch that this will apply to the iPhone too. Of course, you would be able to jailbreak then tether, but I'm not sure how many ordinary users would be willing to do that.
According to my first reference below, tethering will also be capped at five gigabytes with the launch of the iPhone. So, you'll have to pay $30 for tethering five gigabytes a month. The internet on the handset will still be unlimited.
Supposed is the keyword. Once you root/jailbreak the phone, nothing is stopping you from using WifiTether/Tetherme for your tethering needs.
If youre a power user and require over 5GB a months, then youre in trouble. But for most of us that need tethering for those select moments we're away from wifi, its a godsend.
