OdinMonkey will be enabled for the coming Aurora 22 build but disabled once the beta and release channels hit that version. It is still possible to activate the new feature for those channels once their hit Firefox 22 but it needs to be done manually.
To enable or disable OdinMonkey do the following:
Work on OdinMonkey is far from complete yet and it is likely that we will see additional improvements over the coming weeks and months. (via)
If you like our content, and would like to help, please consider making a contribution: