I post a correction on these notes: http://libdlo.freedesktop.org/wiki/DeviceQuirks which over-specify /sys (as well as hard-wiring it) as well as bConfigurationValue.
/usr/bin/dlconfig:
#! /bin/bash
if [ -e "$1"/device/bConfigurationValue ]; then
echo 1 > "$1"/device/bConfigurationValue
fi;
if [ -e "$1"/bConfigurationValue ]; then
echo 1 > "$1"/bConfigurationValue
fi;
/etc/udev/rules.d/60-displaylink.rules
# DisplayLink devices always have the active configuration on configuration #1
SYSFS{idVendor}=="17e9", SYSFS{bConfigurationValue}=="2", RUN+="/usr/bin/dlconfig %S%p"
These cause the VGA adaptor to be intialized properly on each insert.