PC does not have an option for this. However, if you are looking to have the item show as a free item in the shopping cart, the basics of it would be pretty simple to do (if a Control Panel page and db upgraded aren't needed).

Using a settings file, rather than a control panel page and db update, one could control say whether the "promotion" is active, what product get's added as a gift, and perhaps some parameters (min. order amount, maybe?). 

From there, this could be coded into the add to cart "tweener" file, instPrd.asp (if there are no parameters) or to the cart summary page, viewcart.asp if there are parameters (slightly more advanced to do it this way). Only trick here would be reversing it if the parameter where met at one point, but then the cart changed such that it no longer met the parameters.

With this, in either scenario, an automatically applied discount for the price of the item could be set up with the condition that this item is in the cart.

Now that you have me thinking about it, and we are on the cusp of release a new plug-in to enable coupon code/GC code entry on the cart summary (viewcart.asp) page, we could very easily add this in to that plug-in with a few minor tweaks.