IF you want to display current category name on Product details page, you can easily do it. Just added following few lines of code in your view.phtml file.
<?php $_helper = $this->helper('catalog/output');?>
<?php $_category_detail = Mage::registry('current_category');?>
<?php echo $_category_detail->getName();?>
<?php echo $_category_detail->getId(); ?>
<?php $_helper = $this->helper('catalog/output');?>
<?php $_category_detail = Mage::registry('current_category');?>
<?php echo $_category_detail->getName();?>
<?php echo $_category_detail->getId(); ?>
