A few months ago I released a script to install a 32-bit Adobe Flash plugin to a 64-bit Firefox, but it doesn't seem to work in Gutsy beta. Here's an updated one. I upgraded my laptop to Gutsy and used this one to get Flash working.

Edit: I did a complete reinstall later and learned that Gutsy knows how to set this up by itself. So there's no need for this script anymore. And that is a very positive thing!

Just cut and paste it to "flash64.sh", add execute permissions, and run it with sudo.

#!/bin/sh

DEPS="ia32-libs ia32-libs-gtk util-linux lib32asound2 alien"
GWENOLE=http://gwenole.beauchesne.info/projects/nspluginwrapper/files
PLUGIN=nspluginwrapper-0.9.91.4-1.x86_64.rpm
VIEWER=nspluginwrapper-i386-0.9.91.4-1.x86_64.rpm
MACROMEDIA=http://fpdownload.macromedia.com/get/flashplayer/current
FLASH=install_flash_player_9_linux.tar.gz

usage() {
  cat << EOF
A script to install 32-bit Adobe Flash plugin in a 64-bit Firefox.
Usage: $0 [-k]
       -k   keep temporary files
EOF
}

while getopts "kh?" OPT
do
  case $OPT in
    "k") KEEPTMP=1;;
    "h"|"?"|"help") usage; exit;;
    *) echo Unrecognized option "$OPT"; usage; exit;;
  esac
done

if [ "`id -u`" != "0" ]
then
  echo You must be root in order to run this script.
  echo Try: "sudo $0" instead.
  echo For options and help, use "$0 -h".
  exit 1
fi

TMP=`mktemp -d`
cd $TMP
echo Temporary directory $TMP created

echo Installing dependencies: $DEPS
apt-get -qq install $DEPS || exit 1

echo Getting nspluginwrapper plugin: $PLUGIN
wget -qc $GWENOLE/$PLUGIN

echo Getting nspluginwrapper viewer: $VIEWER
wget -qc $GWENOLE/$VIEWER

echo Installing plugin
alien -i $PLUGIN

echo Installing viewer
alien -i $VIEWER

echo Getting Flash plugin: $PLUGIN
wget -qc $MACROMEDIA/$FLASH

echo Installing Flash plugin to /usr/lib32/mozilla/plugins
mkdir -p /usr/lib32/mozilla/plugins
tar -Ozxf $FLASH install_flash_player_9_linux/flashplayer.xpt > /usr/lib32/mozilla/plugins/flashplayer.xpt
tar -Ozxf $FLASH install_flash_player_9_linux/libflashplayer.so > /usr/lib32/mozilla/plugins/libflashplayer.so

echo Creating a wrapper using nspluginwrapper
nspluginwrapper -i /usr/lib32/mozilla/plugins/libflashplayer.so

if [ "$KEEPTMP" = "1" ]
then
  echo Temporary files were left in: $TMP
else
  echo Removing temporary files
  rm -rf $TMP
fi

echo
echo The Flash plugin and wrapper have been installed.
echo You must restart Firefox.