For all the advances mobiles and smartphones have made lately, your actual SIM card hasn't really changed at all.
But SK Telecom has been experimenting with rejuvenating the purpose of the small SIM cards - normally only any good for connecting you to a network and storing a few phone numbers - and created one with a full CPU, 1GB of onboard storage, and Google's Android operating system built into it.
The form factor is pretty much identical to the current SIM card, though naturally it'd take a whole new type of phone to use it. What's fascinating, however, is the notion of cheap "empty shell" handsets and easily transferable operating systems.
Imagine getting your new handset, then transporting your entire OS, applications, music, and content to it simply by plugging in the SIM card. These handsets could even be platform agnostic, only becoming Android, WinMo, bada or any other type of smartphone once your smart-SIM is installed.
It's a fascinating development that, once again, could really shake up the hardware market.