For those of you who want to get free wifi tethering on ICS with T-Mobile Galaxy S2 SGH-T989, you can easily do it by freezing or un-installing the Tethering Provisioning app using the Titanium Backup app.
Just freeze (with Pro version) or just un-install (with free version) and voila, you can use the native wifi tethering app on your T-Mobile Galaxy S2 SGH-T989.
Remember, all data you use “still count” under your data plan, this just allows you to not have to pay additional tethering fees from T-Mobile, which is ridiculous anyways, why are they charging customers TWICE for the internet they paid for already?
Enjoy.