Another thought...AT&T is coming out with new iphone plans to match the data plans for the ipad. Catch is these are postpaid and metered plans:
AT&T's new data plans: What you need to know | Phones | iPhone Central | Macworld
Phones/Wireless Devices: Doogee S90, Isatphone Pro, Amazon Kindle 3G, SkyRoam MiFi device, Karma MiFi device, AT&T Liberate MiFi device
Sim Cards: T-Mobile (Mint), AT&T (Mifi device or Kindle), Koko
Satphone: InMarSat
Broadband US Wireless Data: AT&T postpaid, Sprint (Karma Mobility prepaid)
Broadband International Data: SkyRoam
VOIP: Skype