Just wanted to point out that we have unlimited data from the device. Sprint can't determine what is from the device and what isn't just based on analysis of the port and transport protocol(TCP/UDP) because our devices can use any port they want. Think about it - Mobile AIM by AOL connects to the oscar servers(the protocol that AIM uses) on TCP 5160. Our gmail uses TCP 995 and TCP 465 and TCP 587 (see
here for Google's instructions). It isn't just unlimited data from the browser.
So with that, as far as I know the WMWifiRouter style apps and PDAnet style apps don't report that they're ICS traffic(like ICS does by default - it dials the modem differently). The ICS or PAM (dial #777 from your PC) ways both connect differently and report to Sprint that they're PAM connections. The WMWifiRouter(and HTC Router) and PDAnet apps actually use the phone's normal data connection just like Mobile AIM or the e-mail client, etc - and as such their data is hidden (because our phones can use any TCP/UDP port) in the traffic of what's on our phone. Sprint could PROBABLY do mac address scanning in the packets, since when using NAT the original machine's MAC is preserved(I think) - but I'd bet there's a way to do MAC cloning on our phones which would negate Sprint's ability to use that as a definitive test.
TL;DR - Our phones rock and can do all sorts of cool data stuff. Sprint can't(I'm fairly positive) detect the data if you use WMWifiRouter, HTC Wifi Router, PDAnet, etc.