Enable textual diff of iWork '09 Pages documents. (Forked and updated from a gist that works for older Pages documents)

.gitattributes

*.pages	diff=iworkpages

ConvertPagesToText.sh

#!/bin/bash

# output folder for unzipping the .pages file (really long name to avoid name conflicts)
FOLDER_NAME=$1.unzipped.for.git.diff.text.comparison

# exit if a file already exists with $FOLDER_NAME so we don't delete it later.. (but this is really unlikely)
mkdir $FOLDER_NAME || { echo 'mkdir failed.. $FOLDER_NAME already exists' ; exit 1; }

# unzip the .pages file into the folder
unzip -qq -o $1 -d $FOLDER_NAME

# convert to text and print the text to stdout
xsltproc Pages.xsl $FOLDER_NAME/index.xml

# clean up our work
rm -rf $FOLDER_NAME

git_config

#run this command from your git working directory:
echo '
[diff "iworkpages"]
    textconv = $GIT_DIR/../ConvertPagesToText.sh
' >> .git/config

Pages.xsl

<?xml version="1.0" encoding="ISO-8859-1"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:sf="http://developer.apple.com/namespaces/sf">

<xsl:template match="sf:p">
	<xsl:apply-templates/>
	<xsl:text>
</xsl:text>
</xsl:template>

<xsl:template match="sf:lnbr">
	<xsl:text>
</xsl:text>
</xsl:template>

<xsl:template>
	<xsl:value-of select="text()"/>
</xsl:template>

</xsl:stylesheet>

Including these files in your git repo will allow you to perform git diff on *.pages files!

Apple had changed the format of the .pages files since @bycpx wrote their Gist.