You can download the latest Ubuntu MATE from Softpedia
Ubuntu MATE 14.10 Beta 1, a Linux distribution based on Ubuntu that uses the MATE desktop environment, has been released and is now available for download.It might seem like an official flavor of Ubuntu, but it's not there yet. The Ubuntu MATE developers, which included a MATE and Ubuntu devs, are seeking to gain official Ubuntu flavor status, but they are not there yet. Still, they are following the release schedule for the regular Ubuntu versions and they have now made available their first Beta in the 14.10 series.
"Ubuntu MATE Beta1 is released and represents a big step forward compared to Alpha2, not least because Ubuntu MATE is now sporting new themes and artwork to give it a distinctive look. A number of bugs have also been fixed along the way and a few new ones have been introduced," reads the official announcement.
According to the changelog, a few new community wallpapers have been added (the default wallpaper has been changed as well), a community Plymouth theme has been implemented, a number of Ubiquity have been added, Ambiant-MATE and Radiant-MATE desktop and icon themes have been implemented by default, the Ubuntu MATE LightDM theme has been added, a font created to increase readability for readers with dyslexia called OpenDyslexic is now available, a screen magnifier for individuals with low vision has been added, and colord is now managing, installing and generating accurate color profiles.
Also, the GStreamer backend has been added to LibreOffice, it's now possible to mount disks without a password, the installation no longer fails when there is no Internet connection, support for 3G/4G USB dongles, iPods, and MTP devices has been added, the hardware detection and support has been improved, the .iso image mastering has been improved in order to ensure consistency with official Ubuntu flavors, and the ffmpegthumbnailer, light-themes and ubuntu-artwork packages have been removed.
It's not yet certain whether Ubuntu MATE will receive official status until the October release of the 14.10 (Utopic Unicorn) version, but it's pretty clear that even if they don't get it, Ubuntu MATE will be one of the favorite spins for the community.
You can download Ubuntu MATE 14.10 Beta 1 right now from Softpedia. Remember that this is a development version and it should NOT be installed on production machines. It is intended for testing purposes only.
If you want to test this distribution, you might consider using a virtual environment first, like VirtualBox, and see from there if you want to make a more permanent installation.