From the project web page:
Gobby is a free collaborative editor supporting multiple documents in one session and a multi-user chat. It uses GTK+ 2.6 as its windowing toolkit and thus integrates nicely into the GNOME desktop environment.
Gobby .4 is in the community repo. To install, run
sudo pacman -S gobby
The newer development version .5 (0.4.94-1 at the time of writing) is available in AUR.
packer -S gobby-dev