However, times are changing and some manufacturers are starting to look for even smaller modules in order to save precious space inside their mobile devices. The even smaller micro SIM card, for example, is already in use in all 3G-enabled iPads and the iPhone 4.
Apple is suggesting that SIM cards need to be shrunk even further. Last week, Apple's proposal for a standardized SIM card with dimensions smaller than those of a micro SIM card was submitted to ETSI (European Telecommunications Standards Institute). It didn't take long before Orange, the world's eighth largest telecom operator and one of Europe's most popular wireless carriers, expressed its support for the proposal.
If the idea gets approved by ETSI, having “nano” SIM cards with a smaller footprint will facilitate the production of devices that are too slim for a common SIM card to fit in them. It has been also mentioned that we may see the new modules being used in cell phones as early as 2012. However, that prediction sounds a bit optimistic. Such a transition would probably take longer than that, if it ever gets approved at all.
source: Reuters via Pocket-lint