We know Magento support multiple currency. I have found the solution to check current currency in the Magento site frontend
To get Current Currency
<?php echo $currency_code = Mage::app()->getStore()->getCurrentCurrencyCode(); ?>
If you looking for current currency symbol use :
<?php echo Mage::app()->getLocale()->currency(Mage::app()->getStore()->getCurrentCurrencyCode())->getSymbol(); ?>