iPhone is registered ? Didn't quite get you there. But people buy the iPhone from the Apple Store which is Locked and cannot even be booted to the Home Screen.
Apple does not sell Pre-Unlocked iPhones. The Activation Process takes place through iTunes.
If anyone does need Warrenty then theres only 1 way. Ask a relative in US to buy it from an Official Apple Store, send it to you and if by any chance it breaks down you'll have to send it back to that relative get it replaced and shipped back again.
This is only feasible if you have someone from US constantly coming here every month or so.
So if you have a lot of relatives in US, then you're in Luck. Else take the risk and get an iPhone from Grey Market.
I got some 6 months back....and its working good till now....I don't see why it won't last another 1 Yr atleast so that I can sell it and get the next iteration of iPhone
And btw accr. to me theres no real use waiting for the iPhone in India. For 1 it would still be Locked with some compulsory Costly Plan needed and 2 its pricing too will be atleast 20% costlier than US Pricing.....
and probably no official third party applications either (though, since it will already be jailbroken, you can enjoy the vast library of free unofficial third party software).
I don't think that Unlocked iPhones won't be able to use the AppStore cause the Unlocked iPhone already are able to access the Wifi iTunes Store and buy Music right off it, so I don't see any reasons why the AppStore should act differently....