I connect my MBP through my Sprint 6700 all the time through bluetooth.
It took all of about 1 minute to setup in OSX. I put my phone in 'discoverable mode', had OSX search for Bluetooth devices, found my phone, entered in my 'PIN', filled out my username and password, and whaala; online.
Now I just leave the phone on in my pocket, and the MBP connects no problems.
Some cell phone companys can tell when you do this though. On Sprint they call it 'tethering'. The ability for them to detect is on alot of phones now, but not on mine. Most cellular providers have different pricing for these 'phones as a modem' access plans. I mainly use mine when I'm out at Borders, since I don't feel like paying 10 bucks for internet access after I just paid 5 bucks for a latte. Otherwise if there is wireless around, I obviously do that.
On Sprint, I've done speed tests that have gone over 1.0Mbit, so its pretty fast.
But at any rate, I'm pretty sure Sprint and Verizon are going to be releasing new access cards soon since EVDO Rev A is starting to roll out. Express Card is getting popular, so chances are you will see some express card versions. Otherwise, honestly, I think the bluetooth phone is the best solution, since it saves you money w/o having to buy the card and its one less thing to worry about loosing in you're bag, not to mention is also being able to make calls through the phone from the MB.
