I feel your pain. Kicking myself in the ass for upgrading from 3.0.1. when I had the Carrier file that allowed tethering. This time I was fortunate enough to get it before it was pulled.
Call it contempt, but since AT&T laid me off in March and sent my job to India, I have not one ounce of guilt using this app tethered to my MBP. Along with the 2G iPhone plan on both of our 3GS, they're getting what they deserve nothing more.