The port appeared on the XDA developers forum for Ubuntu Hardy Heron 8.0.4. The owners of a Sony Ericsson Xperia X1, which usually boots Windows Mobile, can install the distro themselves by downloading the install file (1.1GB), put it in the root of the SD card, and run through the setup.

Its not necessary to do anything with soft SPL or hard SPL (Second Program Loader) as far as the bootloader of the device goes. The creator of the port also notes his creation is still in development. Which, by the way, can also be noted by the amount of bugs reported on the XDA developers forum.