[cbr]

In osx I had to do:

     cd /Applications/Google\ Chrome.app/Contents/MacOS
     mv "Google Chrome" "Google Chrome Binary"
     echo '#!/bin/bash
     exec "${0%/*}/Google Chrome Binary" -enable-vertical-tabs "$@"' > "Google Chrome"
     chmod ugo+x "Google Chrome"

This let me start chrome with the "-enable-vertical-tabs" command line switch. Once it was started I needed to right click a tab and choose "Use Side Tabs".

[jannes]

Wouldn't this break after an update?

[andfarm]

Probably worth noting that the vertical tab UI you end up with looks pretty weird (on Mac OS, at least), as it's literally just moving the existing tabs over to the side without changing the graphics at all.

[olifante]

to try it out without making it permanent, just open a Terminal window and enter something like this:

  /Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome -enable-vertical-tabs