mounting usb frustration

[pinniped <cirilo_bernardo@yahoo.com>]

I would suggest reading the USB docs in these links:
http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev.html

It is convenient to use persistence to ensure that all removable USB devices retain their name regardless of how many times you plug them in and remove them. This also allows you to make fstab entries so that any user can, for example, mount your digital camera to download the pictures. You will run into naming problems if the previous device is still in use even if the device node had been removed, but in that case you should be asking yourself what's keeping the device open.  Without using the persistent naming mechanism, your 'sd?' assignments will be based solely on the order in which you happened to plug things in - like USB stick or camera first.