where is the config for dynamically added volumes in nautilus?

[Da Rock]

I've googled for close to a week to resolve this. I know that inserting 
a usb disk (depending on setup and version) causes a knock on effect by 
calling dbus, hal, and maybe more depending. But *how* does nautilus (or 
any other file manager system) find out that the disk is there and put 
an icon in the sidebar ("places")?

I've checked bookmarks, GConf- nothing I can see anywhere tells me how 
this is done. I figured there must be a GConf setting somewhere or 
another backend that stores this otherwise there'd be too many lookups.

Surely it can't be polling for it through hal continuously?

Clues anyone?