Using xulrunner-1.9.3a5pre (with up-to-date conkeror, May 19 21:15), when running "xulrunner 
conkeror/application.ini --daemon" there is this error:

Error initializing.
TypeError: Cc['@mozilla.org/extensions/manager;1'] is undefined
chrome://conkeror/content/extension.js:15
@chrome://conkeror/content/extension.js:15
Console error: [JavaScript Error: "conkeror.handle_command_line is not a function" {file: 
"file:///home/coolio/Conkeror/conkeror/components/commandline.js" line: 22}]
  Category: XPConnect JavaScript

The old extensions manager has been replaced by a new Addons Manager.  We'll have to add support in
Conkeror.  Details at http://www.oxymoronical.com/blog/tag/extension-manager

The command 'extensions' (its handler function show_extension_manager) will need to be updated.

The way we load glue code for extensions (dom-inspector, venkman, noscript, adblockplus) is invalidated
by this change, too.  We depend on extension_is_enabled being a synchronous call, but the new Addons
Manager has an asynchronous api.

http://www.oxymoronical.com/blog/2010/03/How-were-breaking-some-extensions-in-the-near-future

We may have to leave it up to users to load extension glue code themselves in their rc, instead of doing it
automatically.  Loading extension glue through our "conkeror.load.*" prefs no longer seems feasible.

Removed glue-code auto-loading.

https://wiki.mozilla.org/Extension_Manager:API_Rewrite:API

Now that Mozilla supports installing and uninstalling extensions without restarting, it follows that if
Conkeror is to have an automatic mechanism for loading glue code, it also ought to be able to unload
the glue code as the extensions are enabled and disabled.  That either means that we need a convention
for unloading modules, or that we need a convention for disabling features that modules provide, such as
a way to disable commands.