There are officially four carriers for the iPhone in the UK: O2, Orange, Tescos, and as of today, Vodafone. As with the other three carriers, tariffs start at 18 months long, the cheapest being £40/month, providing a free iPhone, 600 minutes and unlimited texting. The plan for 24 months is £35/month, though still more expensive when you do the math. Another 90 quid will get yu a 16GB iPhone 3GS, and £179 on the basic contract gets you the 32GB iPhone 3GS. You can see all the details spelled out at Vodafone's UK website.