iPad and iPhone owners now have another alternative for mobile broadband. Virgin Mobile has added the MiFi, a portable cellular router that acts as a mobile Wi-Fi hotspot, to its pay-as-you-need-it broadband service. Virgin charges $149.99 for the device without a contract. You can purchase mobile broadband in increments as needed.
Virgin Mobile offers four prepaid data plans: $10 for 100 MB consumed within 10 days, while 30-day usage plans cost $20 for 300 MB, $40 for 1 GB, and $60 for 5 GB. There are no overage fees; you simply add another time-limited plan, just as AT&T does with 3G iPad service offerings. Unused data expires at the end of the period. Virgin Mobile is a subsidiary of Sprint Nextel, operated as a separate entity, and uses Sprint's network.
http://db.tidbits.com/article/11396
Another great device to toss in the plane or flight bag. Like with most services, I would hate to have to pay monthly when I only needed it during flying season.
PSSST. You could get this with an iPod Touch and make VOIP calls or non-3G iPad...