Near the bottom of the "Data Only" page: > We’re working hard to add support for GSM devices. Enter your email and you’ll be the first to know when we're ready

Near the bottom of the "Data Only" page: > We’re working hard to add support for GSM devices. Enter your email and you’ll be the first to know when we're ready! So it looks like they're trying to support GSM, which probably involves deals with large GSM carriers, I would guess, since Sprint only uses CDMA.