I too will be coming back to the States in June. Currently, I have Vodafone India service, and the difference between it and US service is astonishing -- Friday after Thanksgiving, I was in the middle of the Thar desert on the back of a camel. It occurred to me to see if I could call my Mom in the States and wish her a happy Thanksgiving. Yup, four bars. No electric lights in sight, but when the sun came up I could see a cell tower on a distant mountain. That 15 minute call cost me about $2.
We have service *everywhere*, it costs six rupees per minute (1.5 cents), and data is cheap and fast. Note that this isn't a government-subsidized plan, it's Vodafone -- they're making money at this. I currently have about $20 worth of minutes on my Corby, and will probably not be able to use it all before we leave.