I found this interesting article:
http://www.isedb.com/db/articles/1480/

It's discussing on GBuy (Checkout) and the fact that credibility will be a key issue here. Credibility that will be more and more difficult for Google to obtain and to retain as Google grows bigger and has more impact on very diverse issues -also international stuff-.

It's indeed confirming the statement in the last sentence of Philipp in the article on Checkout (http://blogoscoped.com/archive/2006-06-29-n64.html).