[CentOS] What replaces /sbin/hotplug in CentOS 5?

What subsystem replaces /sbin/hotplug in CentOS 5?  The older hotplug
package is missing from CentOS 5 and /proc/sys/kernel/hotplug yields an
empty string.  Since hotpluging for standard devices still seems to
work, I presume that something replaces the hotplug helper found on
CentOS 4.  Can someone point me in the right place?  All of my
Googleing points me back to the (obsolete?) /sbin/hotplug subsystem
(Google is just not being helpful!).  I'm guessing udev and/or HAL are
involved somehow, but I am having a hard time figuring out what I need
to do.

Specificly, I have a special USB device (a PI Engineering Rail Driver
Console device) that I have written a daemon for that I need to launch
when the device is plugged in and when the device is unplugged, the
daemon needs to be killed.  For CentOS 4, I used a script fired up from
the /sbin/hotplug via /etc/hotplug/usb.usermap -- what to I use for
CentOS 5 (and eventually CentOS 6)? 


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Robert Heller             -- 978-544-6933 / heller at deepsoft.com
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