xPUD has a boot time of about ten seconds, as you can see in the below YouTube video:
The "Plate" interface consists of four tabs and is created using XUL, and thanks to the binary compatibility with normal desktop Linux applications, you can run your favourite applications on this system that weighs less than 48MB. It could be very useful on netbooks and maybe even media center devices. I can also see this as an interesting second operating system on your normal desktop machine if you quickly want to look something up on the internet or want to play a few .mp3 files.
xPUD is still in heavy development, and they're very interested in your feedback.