http://www.xcomglobal.com/internatio...age/india.html
or take a jailbroken iPhone with an iPhonetrip SIM card and MiWi:
http://www.iphonetrip.com
and before anyone says anything, you can easily beat these rates if you go prepaid over there. India requires registration and I don't think you can do it at the cellphone store. If you have a local who can front for you, you can have the solution in place before you land.
One advantage to iPhonetrip is that it will access multiple networks. Xcom's solution is limited to one network, but is more plug and play.