Currently I am paying $8/month for 1 MB data access (GPRS) to my AT&T Wireless phone. I've used it as a Bluetooth modem to connect my Pocket PC, but after downloading about two ads I go over the limit and then I think it is 2c per kB. It is also consistently slower than dial-up modem and while roaming (driving around) access is unreliable.
Considering the ubiquitous open (and free) Wi-Fi access points it appears unlikely these services will ever be cost-effective.
