I use the code below in my template to see if there is anything in page_content(2). I use this in conjunction with two CSS classes for a right and left column. If there is page_content(2) then use class "content1" for my left column (stored in page_content(1)) and class "content2" for my right column (stored in page_content(2)). If there is page_content(2) is empty then I use the entire width for page_content(1).
Hope this helps.
<?php ob_start(); // Start the outputbuffer
page_content(2); // Next call the block
$content2=ob_get_contents(); // Now fetch the output into a variable
ob_end_clean(); // Clean up old mess and stop buffering
?>
<div id="content">
<?php if ($content2<>"") { // Next test $content2 to see if there is something in it
echo "<div id=\"content1\">\n";
}?>
<?php page_content(1);
echo "\n</div><!-- close div#content1 -->\n";
?>
<?php if ($content2<>"") { // Next test $content2 to see if there is something in it
echo "<div id=\"content2\">\n";
echo $content2;
echo "\n</div><!-- close div#content2 -->\n";
}?>
<?php if ($content2<>"") { // Close the div tag for $content2 if it was used
echo "</div><!-- close div#content -->\n";
}?>