It looks like eBay has now done everything that they can to prevent Google from stepping onto their turf. Just yesterday eBay added the Google Checkout system in their Acceptable Payments Policy terms under “Payment Services not permitted on eBay.” If you violate the policy you could get your eBay account suspended.
While I understand where eBay is coming from, it is funny because Google Checkout doesn’t allow users to transfer money between each other. If you want to perform a transaction it has to be completed at an Online store that accepts Google Checkout. There is a pretty nice list of merchants that are already using the Google Checkout system and some even offer a discount for paying with Google. Maybe someday Google will decide to let users send money to eachother, but for right now PayPal still owns that world.
News Source: BetaNews