Not to crash in on your thread, but I am interested in the same thing this fall. Especially anyone in South Eastern India. Looking for rupees, horse rentals, and wildlife trackers.
This new service seems waesome for prepaid phonecards:
http://www.bitcoinwireless.com/Currently looking for information about 3G/4G USB mobile and how good it works at different locations, prices and possibly if there is a way to fund them with BTC.
I am definitely going to be a customer when they hard-launch! But I hadn't thought about it for travel? Perhaps I could buy a $10 phone when I'm there and load it up. Hmmm...