As you may know, Ubuntu Mate is the newest official *Buntu flavor and has released Ubuntu Mate 14.10, Ubuntu Mate 14.04 and Ubuntu Mate 15.04 (in this order) since it had been adopted in the Ubuntu family.
The Mate desktop started as GNOME 2 fork back in 2011, when the Linux systems adopted GNOME 3. Today, MATE is available by default on Fedora, Arch Linux, Linux Mint and BSD (and forks of this systems).
Recently, MATE 1.10 has been released, bringing support for the X2Go remote terminal solution, updates packages and plug-ins like mate-lockkeys-applet, mate-disk-utility and caja-dropbox. Also, the latest MATE version plans to provide an integrated launcher for Ubuntu 15.10.
For more information about Ubuntu Mate 15.10 and Ubuntu Mate 16.04, watch the below video, from Ubuntu Mate Online Summit:
Worth mentioning facts about Ubuntu Mate & its developers:
Being an open-source project, Ubuntu Mate needs to be backed up by the community and sponsors, but Martin Wimpress (the main developer of the Mate desktop and Ubuntu Mate) showed his recognition to other developers of FOSS as well and made donations, in order to support their projects. He donated $75 to Debian, $75 to Ubuntu, $50 to the Folder Color project, $50 to the Gufw project (both developed and maintained by Marcos Costales), $50 for the Tilda project and $50 to Rico Tzschichholz of the Plank project.
Ubuntu 15.04 is officially supported on the Raspberry Pi 2, this being a huge step further in Canonical’s plan t make Ubuntu the Internet of Things’ OS and has been already included in the NOOBS installation software for Raspberry Pi 2.