Yes they do. One user claims 3 gigs a DAY or 150 gigs a month. BUT you have to use THEIR phones/devices with some exceptions.
NO BYOD for the cool stuff (4g/wimax/Android) . Not without breaking the law.
Or you can TRY the Windows Mobile to Android trick. Google it.
The only prepaid carriers offering UNLIMITED data and meaning it are 1)Net10 Unlimited . 2) Verizon prepaid. 3)Boost cdma and iden. 4)Att Gophone feature phone plan. Oh yeah, and Virgin Mobile. Unthrottled. Uncapped. Thus far.