OK, first off, for 99.9999999% for users this will mean nothing and quite rightly should do as only advanced developers should even think about doing this as it will void warranty and could cause major issues if you flash the wrong type of firmware. Some of the worst case scenario’s could be:

physical injuries or material damage, for example, due to the phone overheating.

but as I said this is worst case!

Now down to the actual story!

Sony Ericsson just announced that owners of new generation of 2011 Xperia™ smartphones (so sorry it will not be available for older devices, although they have not dismissed the possibility that it may come later) and will be available this spring. The current list of devices are as follows:

  • Xperia™ arc
  • Xperia™ neo
  • Xperia™ pro
  • Xperia™ PLAY

There is a catch though, not all variants of 2011 Xperia™ smartphones will be able to have the boot loader unlocked, only “sim free” devices, so if you get the phone from your cell phone provider and/or the phone has a SIM lock, you will not be able to do it on there.

A simple way to check if your device can have the boot loader unlocked, all you have to do is try connecting it to Fastboot, if you can connect to it, then your boot loader is unlockable.

Once the service goes live, you will be able to simply enter your IMEI into a website and get the key, which in turn will allow Fastboot to run the procedure to unlock the boot loader.

source: Sony Ericsson Blog