Once installed, this extension inserts three identical menus with group of links arranged by support channels. One menu is located in the browser's "menu bar", another in the "Tools menu" and the third in the "right-click context menu".
From the extension's Preferences you can enable or disable any of these three menus and also choose which sub-menus and specific groups of links have to be shown.
If the name of your personal page in the Italian Ubuntu Wiki and/or the International Ubuntu Wiki is set in the Preferences, the extension will automatically show the direct links to your personal pages.
The links to IRC channels require an external IRC client associated with the IRC format links (of the form "irc://irc.server.net:port/channel?key"), in order to run it and automatically join the selected channel.
Under Ubuntu you need to install (if not already installed) only "xchat" and "xchat-remote" packages.
Probably in other Linux distributions you need the same packages, but at the moment, I have no means of checking this.
Under MacOS X and Windows you simply need an IRC client handling the IRC protocol (like Colloquy for MacOS X and XChat2 [silverex build, maybe starting from the next build] for Windows, among those freeware).
Under MacOS X, the menus in the menu bar and in the Tools menu, will not show link icons although the icons will be shown correctly in the right-click context menu.

Starting from Ubuntu Hardy Heron 8.04 this extension is available in official Ubuntu repositories through "firefox-ubuntu-it-menu" binary package and "ubuntu-it-menu" source package.