OK, firstly, if you didn't know, SP2010 had a bug in the ddwrt:FormatDate function in XSLT where it assumes that you always use Locale: English (US). So if you live in any other part of the world you can't use this function.
Well, thanks to a bunch of other people and their posts, here, here, and kinda here, there is a way around this using even more XSLT.
So for me, I was calculating differences between dates using strings (yeah I know, probably not the best way but...) and because my Australian Dates were all over the place but I was always calculating them using yyyyMMdd I modified Elio's template for my own.
Hope this helps others, at least as a starting point. Oh yeah, and I hope one of these days MS get around to fixing the root cause!
<!-- ***************************************************************************** -->
<!-- This template fixes an issue where the US think they are the only ones on earth -->
<!-- NOTE: Returns date in yyyyMMdd -->
<!-- If you went to town implementing string manipulation templates to parse a date format out of a parameter you would -->
<!-- be able to return any formatted date, but I don't have the time at the moment -->
<xsl:template name="CustomFormatDate">
<xsl:param name="dateValue" />
<xsl:param name="monthFormat" />
<xsl:param name="locale" select="3081" />
<!-- Split Date -->
<xsl:variable name="day" select="substring-before($dateValue, '/')" />
<xsl:variable name="month" select="substring(substring-after($dateValue, '/'), 1, 2)" />
<xsl:variable name="year" select="substring(substring-after(substring-after($dateValue, '/'), '/'), 1, 4)" />
<!-- Create US Date Format -->
<xsl:variable name="USDate">
<xsl:value-of select="$month" />/<xsl:value-of select="$day" />/<xsl:value-of select="$year" />
</xsl:variable>
<!-- Month Notation -->
<xsl:variable name="monthString">
<xsl:choose>
<xsl:when test="$monthFormat='MM'">
<xsl:value-of select="$month" />
</xsl:when>
<xsl:when test="$monthFormat='MMM'">
<xsl:value-of select="ddwrt:FormatDateTime($USDate, $locale, 'MMM')" />
</xsl:when>
<xsl:otherwise>
<xsl:value-of select="ddwrt:FormatDateTime($USDate, $locale, 'MMMM')" />
</xsl:otherwise>
</xsl:choose>
</xsl:variable>
<xsl:variable name="twoDigitDay">
<xsl:choose>
<xsl:when test="string-length($day) = 1">0</xsl:when>
</xsl:choose>
<xsl:value-of select="$day" />
</xsl:variable>
<!-- Create Date -->
<xsl:value-of select="$year" /><xsl:value-of select="$monthString" /><xsl:value-of select="$twoDigitDay" />
</xsl:template>
