Both vodafone and airtel are launching the iphone in india. However if the experience in US is anyhting to go by then there will be a shortage of supply. So you will need to register with either airtel or vodafone to be amongst the lucky people who can own an iphone.
Here is the links to preorder the iphone in india.
http://vodafone.in/newusers/iphone/Pages/preregister-iPhone.aspx
http://www.airtel.in/iphone3g/
Good TryLinks to Pre Order iphone with airtel and vodafone in india386|just some value|9