For years, the mobile industry and its suppliers have fought an ongoing battle with people hacking mobile devices. This mainly started out with greyhat crackers from the car radio scene supplying tools to 'reset' your car radio PIN code (I'm not sure whether really driven by thieves or end users?).
This matured into SIMlock and IMEI hacking on handsets at the end of the 1990s, driven by very cheap pre-pay handsets. By the way, I was never a big fan of SIMlock, as it just increased targeting of the devices and it just wasn't that sensible as the time we didn't have the hardware available in the industry to protect it properly. Mobile phone theft (and re-enablement) was another driver.
Ordinary users were sufficiently motivated to want to pay to remove their SIMlocks and a cottage industry built up to serve it, supplied by tools from some very clever hackers and groups. This made some people very, very rich.
As skills have grown on both sides, the war between industry and the hacking community has grown increasingly sophisticated and tactical. Today it is mostly being played out within the rooting and jailbreaking community, but it looks like so-called 'kill switch' and anti-theft mechanisms will be a new motivator.
Anyway, I hope you find this taster presentation to the subject interesting!