I don't think Paypal has a monopoly over internet payment processing. There are other businesses offering that service for years before Paypal was up, some specialized in certain services while others are general. For instances, you have worldpay.com , ccbill.com , ccnow.com , 2checkout.com and many others. Not everyone uses Paypal around the world, they probably just have the big market with members of Digitalpoint and probably eBay.
Source: (http://www.e-strategyblog.com/2006/01/paypal_market_s.html) 91% of Americans online, use PayPal, if thats not a monopoly, what is?
Is google checkout only accepting sellers from the US? I am outside USA and want to signup but dont find my country there, it just says Location: United States I cant select the country becuase it doesnt have any drop down list of countries. Talker.