If you want to use Sprint's network without signing a contract, there are a lot of options out there, including its subsidiary Boost Mobile, the American MVNO Virgin, and hybrid provider Republic Wireless, among others. Sprint hopes that there are at least some prepaid customers left out there, because starting on January 25th, it will be offering its service in contract-free flavors.
Update: Sprint confirmed the new service to Fierce Wireless and provided some additional details. There will be no limits on data or bandwidth throttling, and LTE service will in fact be enabled on the Galaxy Victory.
There are only two smartphones that will be available at the beginning of Sprint As You Go: LG's somewhat misnamed Optimus Elite, and the Samsung Victory, conspicuously absent of the "4G LTE" branding that's present on Sprint's current Galaxy model.