This tip comes straight from Gentoo's kernel package maintainer and developer department, and it reflects quite an important change in the behaviour of a core mechanism during the boot process.
The sys-apps/hotplug package is commonly installed on desktop systems in order to provide automatic loading of modules when hardware is plugged in during system operation. As well as automatically loading modules when new devices are plugged in, the previous hotplug releases also scanned the system hardware at bootup and loaded modules for any detected hardware.
Technically, autoloading modules at bootup is not hotplugging, and as such, this functionality has been removed from the latest hotplug release. If you previously relied on hotplug autoloading modules at bootup and wish to keep it that way, then all you need to do is install the more appropriately named coldplug package:
Code Listing 1: Emerge and activate coldplug
emerge coldplug rc-update add coldplug boot
Bear in mind that it is generally safer to include the modules you want to autoload in the /etc/modules.autoload.d/kernel-2.x file, though. Do yourself a favor and switch back to the canonical way if you ever experience problems with coldplug.
From http://www.gentoo.org/news/en/gwn/20041115-newsletter.xml