This module implements PayPal Website Payments Pro which consists of PayPal's Express Checkout and Direct Payment methods.
I ported this to work with RC3 included.
This module does not use the PayPal PHP SDK so the installation is fairly easy.
PayPal have released an official osCommerce contribution for their Website Payment Pro service. I have attached the ZIP here - but it can also be downloaded from the PayPal Tech repository here:
http://paypaltech.com/content/index.php?option=com_remository&Itemid=64&func=select&id=20
