Ubuntu for Phones was announced with much fanfare just a few days ago. While the OS is still in pre-alpha state, there are already videos of the same running on various hardware. Initial videos showed how a pre-alpha software looks like, very buggy and quite unusable, so to speak. But this latest video, which was taken during CES 2013, shows a sudden improvement in the way Ubuntu OS for phones behave. See it for yourself.
Ubuntu Phone OS Demo by Mark Shuttleworth at CES 2013
Ubuntu Phone OS Demo by Mark Shuttleworth at CES 2013
The whole thing was pretty damn slow in the first video demo I saw, which was made by theverge.com I think. And that was just a few days ago. They are definitely making progress.