Canonical has recently announced Ubuntu for phones, which is Ubuntu with a specific interface for mobile devices.
Where can I get phones with this version of Ubuntu pre-installed? If no devices are available yet, where can I pre-order one?
From the 9th February 2015, Canonical's partner, BQ has announced that Ubuntu Touch will be pre-installed and can be purchased on-line. This phone is intended for the European market only.
According to OMG! Ubuntu!
The BQ Aquaris E4.5 Ubuntu Edition is now availble in the BQ web shop for the EU-European market, but still the only model with Ubuntu pre-installed.
EDIT: Some days ago the BQ Aquaris E5 Ubuntu Edition has been released.