specs is the same with ipad mini which i getting it. when jailbreak come we will sure see a tweak for that, just like siri on iph4
The 4S doesn't have the same wifi specs (the 5 and 5s are 2x faster), so I guess it's possible but it would be a lot slower.
It's not just the WiFi speed, it's that AirDrop uses WiFi Direct, which is not on the chip in the 4S. Therefore, it's just not technically possible.
Like the last comment, it is a hardware limitation. Though, it is one of the reasons I was surprised Apple decided to keep the 4S around for another year. I know AirDrop will be one of the highlights of new iPhones in ads, I just think it will sell iPhones, especially to the younger crowd.
Completely different wifi chipset. They might have been able to hack it to work with more cpu/batt. overhead or instable. But Apple wouldn't implement something thats half assed in that manor. Generally all or nothing for them.
They would have to depend on existing wifi network, which is cumbersome. AirDrop creates it's own peer-to-peer, direct Wifi network. And for that, you need dedicated hardware that simply isn't present in older devices. So no, not possible. That's why there's no Airdrop capability between an iDevice and Macs (although given the macs are usually connected to existing network, it would make a little more sense).