Not really the answer I was looking for. Since I'd rather not alter the plugin code, here's a hack to the listing-?.php files that get around it for now:
{jamap locations='{"location":{"0":"<?php echo str_replace("'", "", $this->item->title); ?>"},"latitude":{"0":"<?php echo $ltLocation[0]; ?>"},"longitude":{"0":"<?php echo $ltLocation[1]; ?>"},"info":{"0":"<?php echo str_replace("'", "", $this->item->title); ?>"},"icon":{"0":""}}' zoom='15' map_width='700' map_height='500'}{/jamap}
it strips out (str_replace()) any single quote (apostrophe) characters.
