Want to use one of those new nano-SIMs? You'll need one of these
 

Thinking of hopping on a new contract, but lacking that smaller SIM standard that the iPhone 5 will be packing? You'd best pick up one of these, then. UK carriers, including Three and Vodafone, are already stocking up on these nano-SIMs, and they're also prepping these tiny adapters to ensure the new cards will work across all their devices. These will convert a nano-SIM to both micro and standard sizes, so we'd advise picking one up the same time you visit the phone store. (We've included a glimpse of Vodafone's nano-SIM after the break.)

http://www.engadget.com/2012/09/13/nano-sim-adapter/