No idea, it's one Firefox's killer features I miss in other browsers.

That said, Firefox 3.5 allows one to VERY easily disable the awesomebar: Preferences -> Privacy -> Location Bar.

Awesome, and they even exposed in the UI rather than burying it in about:config.

Their arrogance of baking into the browser what is essentially a bundled extension was ridiculously annoying. My favorite added misfeature: it blacklists URLs with the 'about' protocol handler.

I had been disabling / detuning it piecemeal with extensions + settings to make it less obnoxious. I've come to like most of the completion features most of the time, but the visual presentation and interactive behavior is just fucking awful.

At least it's not as bad as Epiphany: it sorts only in direct chronological order (oldest first!), and in true GNOME style is not customizable in any way. Why the fuck would you ever want that?