This quite puzzles me. A few months ago, a friend of mine gave me his usbstick, and the thing just auto-mounted when plugged into a free USB port. Now I got my own stick, but no auto-mount, and mount /dev/sda1 doesn't work either ("no block device"). hotplug, dbus, hal, and udev are running. Do I need a special udev rule or something?
Is there an easy, step-by-step guide somewhere how to set up Arch linux to (auto-) mount usbsticks? The Wiki entry isn't very helpful.