If you wonder any kind of technical detail of you disk drives (magnetical, optical or also USB mass storage) in Linux udisk is your friend.
tells a lot.
Technically udisks is not Linux (as in kernel), but freedesktop. Freedesktop is the common parent for the various desktops in the Linux world, like e.g. GNOME, KDE, xfce, and LXDE (the newcomer in form of Lubuntu).
udisks is pretty new. It’s not in Ubuntu Karmic, but has been introduced in Ubuntu Lucid. It’s not in openSUSE 11.2. I guess it has been developed to replace hal’s functionality as far as disks are concerned.