As we all know, unlocking an iPhone by yourself (or with the help of your geek friends) voids your warranty, first of all. Next, you may end up with a useless phone, as soon as Apple launches next software update for it... but I am sure there are plenty of people using unlocked iPhones without breaking a sweat. Anyway, it's not about "how to", but "how many"...
How many iPhones have been sold to "unlockers"? Well, according to Poper Jaffray's senior analyst Gene Munster, about 838k iPhones were sold to people buying them with one main purpose in their minds: to unlock them! How did he manage to end up with this figure?
The math Gene Munster used is very simple: Apple reports 3.7 million phones sold in 2007, AT&T announces 2 million activations during the same period, and so we remain with 1.7 million units to think about. Official data says 512k were sold via the European chnnel, and 350k overseas, leaving 838k for the so-called "unlockers", those that used their freedom to choose their carrier, freedom that Apple tried to take away.
Now, it would be really interesting to find out how many of those 838k iPhones were successfully unlocked, and how many are still working without problems, but this kind of data is surely out of anyone's reach, at least for now...