Can't remember where I was in the discussion, so I came back here to post my results...
Let me preface this by saying my results are by using Cingular service on a Motorola GPRS-enabled phone. Other providers and manufacturers may (and will) vary.
I mentioned that I had read up on using the cheaper Cingular MEdia service to get internet access through the cell phone to the laptop rather than paying for one of their expensive data plan ($19.99/mo vs. $79.99/mo for unlimited downloads).
Now, Cingular designed the MEdia plans for browsing on the phone device only, which is why they are cheaper. In fact, Cingular will say that you can't use MEdia to hook the phone up to the laptop to provide internet service. And they try to enforce that saying that you have to use their Cingular Communications software to access the internet on the laptop along with their data plan. And in that software they don't let you change the settings necessary to communicate on the MEdia network. But you can get around that by knowing the correct settings and manually configuring the modem settings and using Motorola's Phone Tools to connect.
So yesterday, DW finally returned from her playing camp nurse on a youth mission trip, so I signed her phone up for the MEdia plan (for some reason, my phone quit responding to the Motorola Phone Tools). Turns out I could choose the cheapest one ($4.99/mo) which is only supposed to give me 1MB/mo of downloads, but the first month is unlimited downloads. We are really only looking for something to give us access while on the upcoming road trip when wifi isn't available. And since I already have the voice plan with them, the MEdia plan is month-to-month - no long term contract.
Anyway, I connected it up, configured the modem settings, and was online. Speed wasn't great - 33K - but faster than the dial-up option I was considering which would have been 1/2 that speed and still cost me $3.99/mo for Cingular to grant me permission to dial-up my own internet provider using my phone and my minutes.
Anyway, for anyone interested in making this work you can read up on it
here and
here.
And of course, you can PM me if you have questions.