It remains unclear whether Internet shopping and same-day delivery can be profitable. Online grocer Webvan collapsed in 2001, largely because it couldn't devise a pricing plan that would pay for the costs of same-day delivery without alienating shoppers unwilling to pay too much extra for the added convenience.
Google is still trying to figure out how much to charge for its same-day delivery service. For the six-month test period in the San Francisco area, consumers won't have to pay a surcharge. Google instead will receive a commission from participating merchants.
The expansion into same-day delivery comes at the same time that Google is preparing to close some of its older online services so it can devote more attention and money to other projects.
The realignment has irked some Google users. The biggest complaints have centered on Google Reader, which allows people to automatically receive headlines and links from their favorite sites, and iGoogle, which allows Web surfers to design a page consisting of the Google search engine surrounded set up other online features, such as local weather reports and stock market quotes.
Google Reader is scheduled to close in July and iGoogle will shut down in November.
Google shares fell $8.47 to close at $794.19 on Thursday.