I am actually in Canada, so I use Bell (This is the plan:
http://www.bell.ca/Mobility/Cell_phone_plans/iPad_data_plans...). I guess it's actually usually around $20 (sometimes I don't go over the 10MB plan if I am on Wifi lots). This is the best I could find for something in Canada.
Let me see that article when you are done! If I move to the US I'll be looking to try the same thing there.
Edit: I am looking at Bolt. Looks awesome. I hope in a few years phone numbers just don't exist. (well, abstracted out).