A range of new certified PayPal payment modules optimized for Oscommerce 2.3+ has been released.

These modules will also work for Oscommerce 2.2+ based shops.

Oscommerce PayPal Modules:
PayPal Payments Standard v3.0
PayPal Express Checkout v3.0
PayPal Payments Pro (Direct Payment) v3.0
PayPal Express Checkout (Payflow Edition) v3.0
PayPal Payments Pro (Payflow Edition) v3.0
PayPal Payments Pro (Hosted Solution) v1.0

Resources:
Oscommerce PayPal Modules Documentation
Oscommerce PayPal module Forum Support