I've installed PCLinuxOS 2010 and have a bizarre mystery for any Linux Sleuths reading this. It begins with an observation: there is no tmpfs mounted on /dev. Mount gives me:
/dev/sda1 on / type ext4 (rw)
none on /proc type proc (rw)
none on /dev/pts type devpts (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)

OK...that's fine since udev can be configured to create/delete nodes right on your hard drive. Then it gets strange...there's clearly a "mount" or overlay of some kind happening on top of /dev. This is evidenced by using the mount --bind option, which I use for live "system" backups and it is quite effective, since it mounts a filesystem free of all it's other mount points...but here's what I observed:
mkdir /bak
find /dev | wc -l
733
mount --bind / /bak
find /bak/dev | wc -l
17087
umount /bak

WTF?!? It's clearly mounted since the "unmounted" dev (in /bak) has 17087 - that's a full /dev/ node complement - while /dev has only 733 items - those created by udev for my running system. This makes NO SENSE!