MyWorld
Executive Member
Google is disabling access to tethering applications in the Android Market at the request of wireless carriers AT&T, T-Mobile and Verizon.
Wireless carriers aren’t fans of these unofficial tethering apps because they allow subscribers to turn their Android devices into Internet hotspots without incurring additional monthly fees.
Without those Android applications, the majority of wireless subscribers will be forced to spend an extra $20 to $25 per month for the ability to tether, or risk compromising the security of their device (to some degree) by running (sideloading) an app found outside of the official Android Market.
http://venturebeat.com/2011/05/04/google-helping-carriers-block-android-tethering/
So, rooting is not longer optional, you will HAVE to root your phone if you want to tether.