Sony's mobile smartphone division is now actively encouraging developers to create, modify and install customised Linux kernels into their latest lineup of phones, including the Xperia Play, the device that was once known as "The Playstation Phone".
In this matter, Sony announced that their 2011 range of phones, such as the Xperia Arc and the Xperia Play, would have the ability to have their bootloaders unlocked. Before the phones were even in stores, Sony launched a dedicated site called "unlock boot loader" for unlocking your phone.
Sony has detailed instructions on how to create your own customized Linux kernel for the devices. The blog goes into great detail on how to build, assemble and flash a kernel using the source that Sony legally has to provide, thanks to the GPL license that the Linux kernels falls under. Customized Kernels are par for the course in the Android world. They're often used to extend the features and functionality of the device, such as allowing it to support additional file systems, improve the camera, increase battery life, and allow for overclocking, among many other things.
Sony reminds that "there is no turning back when unlocking the boot loader. You may void the warranty of the phone, and you will not be able to revert the phone to a locked or original state if you unlock it." However, they have promised to monitor the community and help out where they can:
Sony Ericsson does not guarantee any support on this, but we will monitor the Building the Linux kernel for Xperia phones thread on the XDA Developers forum. However, we cannot guarantee an answer for every question asked in this forum.
If you own any of the above mentioned devices, and wanted to give it a go, read the comple detailed step-by-ste guide here.