I don't know. I might...but then again people are very used to seeing Paypal. I don't know that the fanatic Googlers would make it worth my while to invest the resources into learning and using yet another payment processing system.
I have also been watching Google spread out...all over the place. I don't know when they'll start to stumble, but it's going to happen at some point - that's inevitable. Yahoo used to have a super-clean interface, then they went nuts and started expanding in as many directions as possible (Geocities, Webring, Simplenet, much more). Now Yahoo's just another internet service company - the shiny's worn off. This will happen with Google, eventually. I'm currently signed up to use Paypal, and will soon be moving to a merchant account (yay - enough income coming in to justify the regular expense!!) Signing up for yet another payment option doesn't make too much sense. That doesn't even go into the fact that, depending on the front end, it might not be easy to integrate Google's payment processor with any billing software that's currently available.
I also think that, with the latest rumbles of discontent and muttered questions of hypocrisy among Google's founders ("Don't be evil - unless China forces you to censor yourself or lose out entirely, then it's not really 'evil', but kind of a redefinition of the term"), some former evangelists will begin to shy away from kneejerk prostelytization of anything Google does. For every person who stops, thinks, and says, Well, there wasn't a win-win scenario in that situation, there are folks who are pretty disillusioned with Google right about now.
