Different Sim Sizes

When available in Australia my husband and I are looking at buying the new iPhone 4S and doing a bit of a shuffle with the Sim Cards. He has a Samsung Ultra Touch (what a nightmare!) and will be taking over my iPhone 3GS, whereas lucky me will be getting the new iPhone 4S. Will it be possible to change the Sims of the iPhone 3GS and the new iPhone 4S. The Samsung Ultra has the same size Sim as the 3GS so no problems there. Any advice on how to transfer either the card or the data from the 3GS to the 4S would be greatly appreciated.