Don't quote me on this but I think tiered data plans are coming soon, probably before the summer (iphone 5 release?).
From the past, $15 for 250 MB, $30 for 5GB (?) , and it gets up to $60+ for their "corporate" plans.
Now, that was for 3g so maybe they'll bump up the price a little for 4g. I wouldn't be surprised if they do that because VZW is a soulless, money leeching who*e. Hopefully we can keep riding on the "unlimited" data plan when Verizon changes their policy.