Zero Personality is a Firefox extension for disabling Personas, both installation and the auto-preview that happens when you roll over an image with the mouse.
It is available from [addons.mozilla.org] 1
No configuration options are currently available.
When Firefox 3.6.2 was released, Mozilla decided to add Personas to the What's New page that every user gets to look at. This is my overreaction.
Added namespacing per AMO feedback. Back in the queue!
Uploaded to AMO.