Among the features to MATE 1.4 is a DropBox package for its Caja file manager (a fork of Nautilus), new themes, support for Bluetooth file sharing, fast alt-tabbing when compositing is enabled, mate-character-map and mate-icon-theme-faenza are now available, mate-screensaver can now handle GDM user switching, libwnck is forked as libmatewnck, and there's many Caja file manager improvements.
The MATE Desktop 1.4 release announcement can be found on the MATE-Desktop.org blog.
The Road-map for this GNOME2 fork yields more Caja file manager improvements in the next release, mate-video-player as a Totem fork, and then further out they will begin starting to port these applications from GTK2 to GTK3. They're also looking to port programs from MateConf (their GConf fork) to the GNOME3 GSettings too.
For those that missed it, the MATE Desktop will be available in Fedora 18.