This post is sent from my laptop, using a brand new cellular data card. All right, it is not so new. I bought a second-hand Sierra Wireless Aircard 875 PCMCIA 3G modem, Cingular branded. The card has excellent Linux support, and Fedora has no trouble recognising it. Just insert the card, run network configuration applet and add a new modem.
I spent Rp 945,000–now about 90 US dollars–and it worth every penny (sorry, Indonesian cents).