vim multiuser editing?

Sorry no such feature, found this advice:

The common suggestion is to use a shared "GNU Screen" session:

http://groups.google.com/group/vim_use/browse_thread/thread/f502e7783038d484/c4603374d2e752b2

to do collaborative editing in Vim. However, it's a bit tricky because it's modal, so if one person changes modes, the other person has to adapt accordingly.

Sorry to dig out this old question but as I bumped on it and found an answer here it is:

Have a try with https://github.com/FredKSchott/CoVim

EDIT: this project is now archived on Github, last change was made on 2017

I don't think so, because Vim creates a swap file any time you open a file. This swap file helps if you want to recover after some sort of an error. When the second user opens the file, his or her Vim will see the swap file and get an error and the options to ignore, delete, recover, etc. I don't think that both users would be able to simultaneously edit this file.

I think the best way to have both users work on the same file is to use a version control system. I like mercurial (good tutorial here), but subversion and git are the classics.