40 
Remember nano-SIM cards? The ones which make micro-SIMs look gargantuan and are so small that it’s almost like what’s the point? Well they’ve just been approved by the European Telecommunications Standards Institute, which means at some point in the future, they’ll likely be in your smartphone.
According to The Verge, the new design is 40 percent smaller than the current microSIMs, and is designed in such a way as to allow backwards compatibility with existing devices. Of course, this didn’t conclude without a spot of controversy. Apple, a proponent of this evolution, had wanted their own design spec to become the official one. But handset makers such as Motorola, RIM and Nokia objected, and came up with a compromise design of their own; a design that would become the final spec.
So, who else is looking forward to that frustrating moment a few years from now when we lose our SIM cards while trying to swap phones? [ETSI via The Verge via MacRumors]
NanoSIMs For the iPhone 5 Start Arriving With Networks
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Apple's Nano-SIM Comes Under Fire From Nokia, Motorola and RIM
I never understood the whole sim card thing; to me it looks like a solution to a non existent problem. Why can’t mobile phones be like land phones where one can just connect it to any network that works with that phone?
If I get you right, I think the issue with SIM cards is that if you didn’t have them you would have to hard-code/bake the SIM into the phone, so it would essentially be coded to a particular network… kinda like a bank card; they all do the same thing, but for security etc each issues their own. You couldn’t (easily) sell the phone on etc.
Now as for the design changes… I can’t see the point. The things are bleedin’ small enough as it is.
Nano sims are still huge compared to other internals, look at this photo of the 4S logic board: http://guide-images.ifixit.net/igi/dCidpYqpnbZ2JiDS.medium
The biggest thing on the board is the nano sim card tray, it’s bigger than the A5 chip that contains a dual core processor and graphics.
Think the reason why they want to make the card smaller so the hardware to read it would be smaller and take less space on the phone.
Sorry, I can’t help but point out some major mistakes in this article. Firstly, it was actually Apple’s design that won out in the end, though by that point both parts were nearly identical except for one tiny groove, after each design had been tweaked and headed closer and closer to the other design. All this is stated in your source article from MacRumors:
http://www.macrumors.com/2012/06/01/new-nano-sim-standard-approved-40-smaller-than-micro-sim/
To be honest, I don’t really understand why it’s taken so many iterations to get this right. As far as I understand, the chip itself hasn’t changed in any of the designs with only a reduction in the plastic around it, so why, when they first realised they needed to slim them down, did they not just cut away all the plastic – which pretty much seems to be what they’ve now done?