I purchased the Droid X right when it came out and got the "unlimited" data and hotspot options. I just received my first bill and it has $250 worth of data charges on it. I called customer support and learned that hotspot data is not in the unlimited plan. In fact, they do not offer a data plan for using the phone as a wifi hotspot - it's pay as you go.
This was the whole reason I bought this phone - to get the hotspot. I even turned in a wifi card I had with Sprint. Even the customer support supervisor admitted it does not make any sense. What a disaster..... #fail