These "sources" seem to know quite a bit -- they also claimed that Vodaphone was being considered for an Australian release, and said that "multiple carriers" might even be likely. Of course, don't forget your grain of salt on this one -- Vodafone officials denied any knowledge of the deal. But it's very true that India is one of the biggest players in the "grey market" for iPhones, so a deal there, with Vodafone or another carrier, wouldn't be unexpected at all.
There is one catch -- apparently the price specified by Apple sources is around Rs 28,000, which is a whopping $700 US (for comparison, the price in the UK was £300 on release before the price drops, which comes to $599 US). So if these sources are legit, anyone wanting to take advantage of a Vodafone deal won't be doing so cheaply.
Thanks to everyone who sent this in!