I'm not sure what specifically Verizon Blocked with their Droid X 2.3.3 GB update or with the X2 2.2.2 "Froyobread" (I call it that because it claims it's Froyo but acts very similar to GB and has the same tethering block and setup as GB along but with an added app shortcut in the drawer) but I believe that they've programmed it to interrupt all non-authorized attempts at broadcasting a wifi network on the "192.x.x.x" and "172.x.x.x" network ranges. However, the "10.x.x.x" range may have been left untouched due to it being a popular range used for VPN tunneling, a feature built into the phone.
Umm... you're the only one reporting this problem... I've had no trouble running a tether over 192.x.x.x, so I'm pretty sure there's no block. I suspect your issue is centered on the PC, not the phone.
Talk like this is just going to spread false rumors.