I agree completely, but to tether at that speed...that might be interesting.
Tethering might be interesting, but the phone battery will definitely give out quickly.
None of this is going to matter in 2 years. There will be phones with Wimax, LTE, and 3G radios so data speed access won't be an issue. TMo and ATT using GSM current advantage is being lost because there are so no HSPA+ phones capable of the top end speeds right now. Tmo has one coming out later this summer/early fall, but TMo's too small to get phonemakers to develop devices for it. TMo's best bet would be to try to get some WPS7 phones that are HSPA+ ready. ATT's never going to develop HSPA+ so again the phonemaker and phone availability issue is going to void this tech.
I can say, it WAS on 3G, it WAS as real as I could imagine. It WAS my second test that went to amazing speed. I can also say it doesn't cache long, because I ran it again later and got much lower speeds. (though still too high). My results were in how the RIM servers handle the blackberry.