New England - Best carrier for short-term iPhone 4 plan in Boston?

I will be in Boston for 2 weeks in October and have no interest in being hosed for roaming voice/data charges by Rogers (my beloved home carrier). I will hopefully have my brand-new unlocked iPhone 4 by then - any recommendations for which carrier can quickly provide a pay-as-you-go micro-sim card?

Thanks
MMD

Only AT&T and T-mobile use sim cards, and the latter doesn't do micro-sim cards (though apparently it's not difficult to cut it down to size). Both do payg, but not sure about exact current terms.

tb

There has been several people who have used prepaid sim cards from

www.mrsimcard.com

If you search for mrsimcard in the forums you will find some of the threads. They repackage / remarket tmobile and apparently do a much better deal.