> I'm trying to find all processing instructions that occur 
> between the current node (which will always be a text node in 
> this case) and the next text node (in document order). 

When you say "next", are these nodes all siblings?

If so,

<xsl:variable name="next" select="following-sibling::text()[1]"/>
... select="following-sibling::processing-instruction()[. &lt;&lt; $next]"/>

Regards,

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