You can look for a way to do this in a near future, through our conditional merge codes. An example of what you will be able to do is something like this:
##IF[CartIsEmpty]##
Your cart is empty.
##ELSE##
<a href="ShopCart.aspx">Click here to calculate your shipping costs.</a>
##ENDIF##
This has been added into our beta version, but is not yet widely available.
Chris Allen
Software Developer
AmeriCommerce