// you can use any value including objects.
set_query_var( 'var_name_to be used_later''var_name_to_be_used_later', 'Value to be retrieved later' );
//Basically set_query_var uses PHP extract() function to do the magic.
then later in the template.
var_dump($var_name_to be used_later$var_name_to_be_used_later);
//will print "Value to be retrieved later"
I recommend to read about PHP Extract() function.