At the moment, while onlyCinnamon and Mate editions.
Linux Mint 18.3 "Sylvia" is a version based on Ubuntu 16.04.3 LTS and linux kernel 4.10 (with the possibility of switching to the 4.13 kernel in the Update Manager => View => Update Linux kernel). And as Ubuntu 16.04 LTS is the distribution with long term support until 2021.
What's new, you can read the official blog of Linux Mint: Cinnamon, Mate.
Already now you can download the stable iso images of Linux Mint 18.3 "Sylvia" Cinnamon and MATE 32 and 64-bit, ftp mirrors linuxmint.com on the following link http://ftp.heanet.ie/mirrors/linuxmint.com/stable/18.3/
And, very soon, it will be possible to download the package from the main page linuxmint.com and via torrent.
May the Force be with you,