Yahoo and Paypal are promoting merchants who advertise with Yahoo and offer Paypal’s Express Checkout with a special logo. The new Yahoo! Paypal Checkout service offers merchants free Express Checkout processing until the end of the year, and US$100 worth of advertising on Yahoo: it’s all very reminiscent of, and presumably designed to compete with, Google Checkout’s offers. The new service is part of an ongoing partnership between Paypal and Yahoo. Under an agreement struck last year, before Google had officially launched their Checkout service, Paypal provide Yahoo’s Wallet service, where users can store billing and shipping information.