How to replace Safari 6's inspector with WebKit's inspector.

one-line-install.sh

curl -L https://raw.github.com/gist/3880960/db03e2ba7e519f7431f35aaddcf4a5899669aec4/revert-safari-inspector.sh | bash

revert-safari-inspector.sh

#!/bin/bash

WEBKIT_DMG="WebKit-SVN-r121872.dmg"
WEBKIT_DOWNLOAD_URL="http://builds.nightly.webkit.org/files/trunk/mac/${WEBKIT_DMG}"
WEBKIT_DMG_PATH="${HOME}/Downloads/${WEBKIT_DMG}"
WEBKIT_MOUNT="/Volumes/WebKit"

WEBKIT_RESOURCES_PATH="${WEBKIT_MOUNT}/WebKit.app/Contents/Frameworks/10.7/WebCore.framework/Versions/Current/Resources/inspector/"
SAFARI_RESOURCES_PATH="/System/Library/PrivateFrameworks/WebInspector.framework/Versions/Current/Resources"
SAFARI_RESOURCES_BACKUP="${SAFARI_RESOURCES_PATH}_backup"

WEBKIT_INSPECTOR_FILE="${SAFARI_RESOURCES_PATH}/inspector.html"
SAFARI_INSPECTOR_FILE="${SAFARI_RESOURCES_PATH}/Main.html"

WEBKIT_INSPECTOR_CSS="${SAFARI_RESOURCES_PATH}/inspector.css"

DISK_MOUNT_REGEXP="/dev/disk[0-9]*s[0-9]*"

if [ ${1} == "--revert" ]; then
	if [ -d ${SAFARI_RESOURCES_BACKUP} ]; then
		echo "Reverting to Safari Inspector"
		sudo mv -R ${SAFARI_RESOURCES_BACKUP} ${SAFARI_RESOURCES_PATH}
	else
		echo "Warning: ${SAFARI_RESOURCES_BACKUP} not found. Exiting."
	fi

	exit
fi

if [ -f ${WEBKIT_INSPECTOR_CSS} ]; then
	echo "You've already installed WebKit Inspector."
	exit
fi

if [ ! -f ${WEBKIT_DMG_PATH} ]; then
	curl ${WEBKIT_DOWNLOAD_URL} -o ${WEBKIT_DMG_PATH}
fi

echo ""
echo "Mounting ${WEBKIT_MOUNT}"
MOUNT=$(hdiutil attach ${WEBKIT_DMG_PATH} | grep ${WEBKIT_MOUNT} | grep -oe ${DISK_MOUNT_REGEXP})

echo "Backing up ${SAFARI_RESOURCES_PATH} -> ${SAFARI_RESOURCES_BACKUP}"
if [ ! -d ${SAFARI_RESOURCES_BACKUP} ]; then
	sudo cp -R ${SAFARI_RESOURCES_PATH} ${SAFARI_RESOURCES_BACKUP}
else
	echo "${SAFARI_RESOURCES_BACKUP} already exists!"
fi

echo "Copying ${WEBKIT_RESOURCES_PATH} -> ${SAFARI_RESOURCES_PATH}"
sudo cp -R ${WEBKIT_RESOURCES_PATH} ${SAFARI_RESOURCES_PATH}

echo "Moving ${WEBKIT_INSPECTOR_FILE} -> ${SAFARI_INSPECTOR_FILE}"
sudo mv ${WEBKIT_INSPECTOR_FILE} ${SAFARI_INSPECTOR_FILE}

echo "Unmounting ${WEBKIT_MOUNT}"
hdiutil detach ${MOUNT} -quiet

echo ""
echo "Safari Inspector has been swaped with WebKit Inspector. Enjoy."

exit

Even easier:

curl -L https://raw.github.com/gist/3880960/d44d06472f6eda9042513c1681b1c05cfb5558ab/revert-safari-inspector.sh | bash

Updated:

curl -L https://raw.github.com/gist/3880960/db03e2ba7e519f7431f35aaddcf4a5899669aec4/revert-safari-inspector.sh | bash