With Sprint, Yes you can get free data.
It does appear that you can leverage the new Alltel roaming agreement with Sprint to your advantage. By inserting Sprint SIDs into an Alltel PRL (currently done by a select few hackers), you can access EV-DO data services anywhere in Sprint’s EV-DO coverage map. Alltel will be offering this to all of its customers in an upcoming free update, as Alltel prepares to become a national wireless provider (riding on the back of Sprint’s national network).
Since Alltel U Prepaid offers free #777 access through its Axcess Mobile Apps (a la Get It Now on Verizon), it does appear that a pay-per-minute user can get free EV-DO access.
Unlike Sprint and Verizon, Alltel has not deployed Modem NAI, a system used to ensure that only customers that pay for Phone-As-Modem plans are allowed to use their phones as a modem with a laptop or desktop computer. This means that by tapping Alltel, users will be able to access Sprint’s EV-DO network for virtually any use.
How Alltel can block this is not quite clear. It will take severe NOC renovation to deny prepaid users data roaming. What will most likely happen (once this starts being abused) is that Alltel will start charging by the minute for #777 access. This is what Verizon Wireless does currently, but blocks EV-DO access with Modem NAI.
Even then, this is still a potential nightmare for Sprint. Users will be able to tether to EV-DO by using a postpaid plan and just minutes, and prepaid users who want to ride on Sprint as a secondary phone will only have to pay $.15/minute.