Canonical, the group that maintains the Ubuntu distribution of Linux, have announced a touch-centred phone UI for Ubuntu. The plan, apparently, is that the phone will be able to connect to a keyboard, mouse and external monitor - which should, in theory, convert it into a full desktop PC.
There are a couple of hurdles in the way, though. Firstly, the early videos and previews I've seen have been less than glowing. They all realise it's a pre-alpha, first-release version of the OS, but the lag and reliance on gestures have caused concern. The gestures in particular don't seem quite right to me; they might be more useful once the lag's worked out, but I get the impression that the swipe-down gestures in particular were thought up for use by a mouse - the target icons are minute, which has the potential to make finger navigation a right pain.
The second, in my opinion much more dangerous, problem they face is the timeline. Ubuntu Phone devices aren't going to be available until early 2014 - over a year away. That's assuming, of course, that there aren't any unexpected delays or manufacturing problems - which would be unheard of outside Apple's processes.
A long lead in, giving developers time to get used to and create software for the OS, isn't necessarily a death knell for Ubuntu on phones, but they've basically given everyone else in the smartphone market a list of features that they can start copying now to undermine all of Ubuntu Phone's USPs by the time it launches.
Palm, and later HP, made similar premature announcements about webOS that meant once the devices hit the market their features were either old news or had been effectively incorporated into Android, iOS or both.
Obviously the phone-as-full-PC feature is going to be difficult for Apple or Google to rip off, without a big-screen version of iOS or Android currently on the cards, but I'd expect the majority of smartphone users aren't looking for that as a primary use for their next device. The gesture stuff, which is in a stronger position to change how people use their phone day to day, is much easier for someone else to nab in the next twelve months.