Same thing was driving me crazy for a while last night, the answer was staring me right in the face all the time but it was so simple I couldn't see it until the very last minute then it hit me.
In the include file from smarty level do this:
Lets say you want to include the above in product.tpl:
Put
Code:
{include file="customer/main/whatever.tpl" productcode=$product.productcode}
In product.tpl
Notice I'm passing the productcode via smarty.
Now in whatever.tpl
Put
Code:
{php}
$productcode = $GLOBALS['smarty']->_tpl_vars[productcode];
include("http://www.mysite.com/d/{$productcode}.php");
{/php}
And your home and dry.
Note: Include() is dependant on server PHP configuration, looks like you're trying to pull in a product page from another site so keep in mind PHP may be set up in such a way that it doesn't let you do remote includes.