I am working towards netlink socket support. I'm sorry it has taken so long. I am still here.
ACPID is a completely flexible, totally extensible daemon for delivering ACPI events. It listens on a file (/proc/acpi/event) and when an event occurs, executes programs to handle the event. The programs it executes are configured through a set of configuration files, which can be dropped into place by packages or by the admin.
If you use ACPI, you should use acpid. The man page for acpid has lots of useful information, read it :).