/dev/blog » Using udevadm to gather information about specific device.
Usually, udevadm requires the sysfs device path of the device in question. But you can also ask udevadm which device path belongs to a certain device node. This gets really helpful if you combine these two queries.
Example: You want to get a list of attributes for a specific device. You do not know the complete device path; all you know is the device node /dev/sdb:
A nice document describing how to use this information to write udev rules can be found on http://www.reactivated.net/writing_udev_rules.html.