> It would be really useful if it returned the actual dateTime 
> at the time of the call so you could implement a progress 
> reporting feature in the transform - you could say how many 
> records were processed in a given time and based on that 
> suggest when the transform might finish.

It wouldn't be as useful as you think. Let's say you use an extension
function that does this, as has been suggested:

<xsl:variable name="startTime" select="xx:current-dateTime()"/>
... do some processing ...
<xsl:variable name="endTime" select="xx:current-dateTime()"/>
<xsl:message select="$endTime - $startTime"/>

The final result will be a negative duration, because Saxon will evaluate
$endTime before it evaluates $startTime.

Michael Kay
http://www.saxonica.com/