Unionfs for Linux?

Lukey Boy asks: "A machine in my network is currently a large fileserver, and holds many hard disks full of media (namely my music and what not). Each drive is running a standard EXT3 filesystem with the same layout (/media, /media/mp3, and so on). My problem and question is how do I join these drives to look like a single hierarchy? I would like to, when I check /all/mp3, view the contents of each drive in this combined directory. FreeBSD has a unionfs filesystem type which supports the unioning of two drives - but only two is a fairly bad limitation, especially when I add a new drive. It appears that Al Viro is working on a unionfs for Linux 2.5, with again only two mount points supported. I was also considering using the Linux Volume Manager system, or possibly a software RAID striping arrangement; does anyone have any experiences doing anything similiar? Is there any decent inheritable filesystem (IFS) available for Unix machines?"