Hey I don't know if this been posted but i figured out how to get the sprint px 500 wireless card to work on a 15in powerbook. I 'm surfing with it right now i will try to post a tutorial for everyone tomorrow.
It's their PowerVision 3g/EVDO data service. It uses towers just like the phone service but the speed is quite nice, especially where they're enhancing the equipment to revision A.
I used my wife's Sprint card while traveling over the holidays. Worked great! No real setup, OS X found the card and set up the option for me to dial in, and off I went!