Droid Life updated the 1-year contract price on the TB. It is now $330, no longer $350. Not much difference, but it helps. From what I've been reading lately, it sounds like VZW will keep the same $30/month unlimited data plan, even for 4G/LTE, at least initially at launch. If they do that, not only will they steal iPhone customers from ATT, but they could get some EVO customers from Sprint as well. It would be a smart strategy. Of course, this is still speculation from forums and what "employees" have posted. Regardless, I suspect we will know for sure in a week or so.
I would not be surprised if they jacked the price up for LTE or instituted tiered-pricing plans several months down the road though. And hopefully if and when they do, people who have existing contracts will be grandfathered in (ie. will not have to pay the new rates until their next contract renewal).