Currently there is no mechanism in the DataExchange Query Language to return the results sorted. We think that your enhancement suggestion is an excellent idea and are moving to make the changes to DataExchange now for all methods.
Depending on you implementation (i.e. how you are using the XML on your page) you should be able to come up with a XSLT solution something like the following in your xsl template would probably work:
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:template match="individuals">
<table>
<xsl:for-each select="individual">
<xsl:sort select="@lastUpdatedDate" order="descending" />
<xsl:if test="position() < 150">
<tr>
<td><xsl:value-of select="@firstName" /></td>
<td><xsl:value-of select="@lastName"/></td>
</tr>
</xsl:if>
</xsl:for-each>
</table>
</xsl:template>
</xsl:stylesheet>
Let me know if you have any questions.
--Nick