Fujitsu just updated their LifeBook T5010, T1010, P1630, and T2020 with AT&T BroadbandConnect (HSUPA) support. And better still, some models will support EVDO in a few months (Sprint or Verizon's 3G technology, carrier unannounced). [Yahoo]
no. You would need the separate Broadband Connect plan at $60 a month. The Broadband Connect "unlimited" plan realistically limits you to 5GB/mo until they start to either throttle your bandwidth or turn off the service and kick you off your plan. The AT&T 3G unlimited data plan only pertains to data that is transmitted to your 3G phone. AT&T has tethering plans, unfortunately, for now the iPhone 3G is untetherable.