Thanks for the info all! I am not jumping the gun until I know anything about the 4G plan and the price.
Here is what I got from my chat with a Verizon representative a couple of minutes ago:
Please hold for a Verizon Wireless sales representative to assist you with your order. Thank you for your patience.
A Verizon Wireless online pre-sales specialist has joined the chat. You are now chatting with (VZ)
VZ: Hello. Thank you for visiting our chat service. May I help you with your order today?
You: I noticed the HTC Thunderbolt ad/pre-order in today's Best Buy circular.
You: I wondered what the data plans for the 4G phones will cost.
VZ: I would be more than happy to assist you with your questions, The data package plan for the Thunderbolt will be $29.99.
Chad: Is that the same as the data plan for the Original Droid (which I have now)?
Chad: (I don't look that closely at my statement each month.)

VZ: Yes it is.
VZ: Yes
Chad: GREAT news! Thank you! ... By the way, do you have any idea when the Thunderbolt will come out?
VZ: Unfortunately, we do not have that information at this time, but you are able to sign up for our Email Updates and they will let you know if anything comes up. Hover over the Support tab and you will be ale to click on the link from the list.
Chad: OK. Thank you for your help!