Some pointers:
The complete Gentoo Linux 2.6 migration guide
Gentoo udev Guide
Notes:
* famd went crazy after the kernel update (it wrote about 100 lines of text per second to /var/log/messages). ’emerge fam’ solved it.
* udev doesn’t seem to recognize external USB drives that are plugged-in at boot-time already. So in addition to ‘hotplug’, I had to install ‘coldplug’:
# emerge coldplug
# rc-update add coldplug default
# /etc/init.d/coldplug start