Mobilin ( Mobile Linux) is a project by intel running linux on MIDS & netbooks based on atom processor and similar processors. Currently the latest release are in version 2.1. Now it is under Linux Foundation. Its just not another damn distro. Its an optimized version with faster boot time and low power consumption. They have now included the support for In vehicle Infotainment.
Currently package format is rpm based. But ubuntu should not worry as there is a mobilin remix edition having dpkg format though mobilin's site does not mention it.
One of the great thing about the project is Moblin Garage installer through which you can easily installed application by browsing ( though in your desktop you can do it using packagekit but here user interface is much better). But you can't run it on some device not supported.
As for security I think it is top notch as they are using sandboxing (which is being used in chrome OS also).
I do know there are many projects going on optimizing Linux to run on MIDS/embedded devices. Infact some distro also have a separate divisions for embedded systems and tablets ( even if device don't come with it).