Your phone's next SIM card will almost definitely be smaller than the one you (may) have now.
Let's break down that sentence to have it make sense.
Your phone (dumb and smartphones alike) will be getting smaller SIM (Subscriber Identity Module) cards. They are small, plastic smart cards that carry your cell phone 's account information.
All GSM-based phones have used SIM cards for years. CDMA-based phones (the standard used by Sprint and Verizon) didn't need them. Very recently, phones which run on the new high speed, 4G/LTE data networks have SIM cards too.
For a long time SIM Cards were the size of a thumbnail (on the left in the photo). But now, with smaller, thinner designs something smaller was needed. Even the tiny micro-SIM cards (on the right in the photo) now being used in some new device (iPhone 4, Nokia Lumia), take up too much valuable space inside a handset.
Apple came up with plan to shrink the micro-SIM even further. Motorola, RIM and others submitted a slightly different super-small design.
Today, the decision. ETSI (European Telecommunications Standards Institute) announced that your next SIM card, the nano-SIM officially known as 4FF (Fourth Form Factor) will be 40% smaller than today's smallest SIM. It will also be backwards compatible with all current SIMs. That means you'll be able to get a bracket to fit the new SIM properly inside today's phones.
No word yet on exactly when we'll see next-gen phones that take advantage of the new mini-micro cards. I predict it will be very soon. Possibly even iPhone 5 soon.
For the record, the cellular industry issues more than 4.5-billion SIMs each year.