add short code to fetch sku

I am sure this is easy, but I just have no clue how to achieve this:

I want to add the sku of a product in more than one place, in addition to the “normal” place. The place where it’s added should be flexible.

So I thought of creating a short code via functions.php, something like [showsku] that I can add wherever in the product page, that will output something like “SKU: xxxxxxxx”.

Any suggestions on how I can achieve this?

Thanks!!!

http://wordpress.org/extend/plugins/woocommerce/