Sony is consumer friendly when it comes to flashing Android ROMs. Today continues that trend as the company has just released a tool that will allow Xperia modders with an unlocked bootloader to reflash Sony's stock ROM. The tool, available on Sony's developer site, currently supports the Xperia S, arc, and arc S.
The tool is currently in beta and Sony is working on increasing the number of supported devices. It's a pretty simple task, something that should be easy to people who are messing around with ROMs and bootloaders in the first place. A video how-to is included below for your viewing, and modding, pleasure.