Google has just posted a bit more information regarding their payment service on their Blog. It is pretty vague at this time.
Basically it appears that you will be able to link your Credit Card information to your Google account and then pay for services (mostly from Google). Google will handle the payment process. This especially makes sense for Google Base where Google has recently introduced a payment feature.
It works like this: You buy something from someone on Google Base, pay for it with your credit card (linked to your Adsense Account), Google receives and handles the payment, Google then pays the recipient.
This however seems to be just the tip of the iceberg.
Looking ahead, we want to continue building payment services that meet the needs of Google users and advertisers. We expect to add payment functionality to Google services where our users need a way to buy online. For us, it's all about bringing our users a better online experience whether they're searching or buying.
Now, if that isn't a hint of things to come, I'm not sure what is....
