Well not the most timly post but whatever... ;-)
Actually that can be done pretty easily. You set up a normal shopping cart script but instead of sending the information to cybercash etc.. You incorporate shopping cart info into your paypal URL.
something like this:
$user_email = "firstname.lastname@example.org";
$item_name = "Order number 132453";
$order_id = "aqwe-23452";
$order_price = "300";
$shipping = "12.50";
$thank_you_url = "http://www.jrmstudios.com/thankyou.html";
echo "<a href=\"https://secure.paypal.x.com/xclick/business= $user_email&item_name=$item_name&item_number=order_id &amount=$order_price&shipping=$shipping&return= $thank_you_url $order_id\">Checkout</a>";
The customer will not have a full list of the stuff they purchased at checkout time, just an order# but It is a very good option for smaller shops IMHO. I'm going to give this a try in place of ccNow on a clients site.