Mountain View -- Google's (GOOG) same-day delivery service will make its public debut to most of the Bay Area on Wednesday morning, as the search engine giant becomes the latest tech company to deliver online purchases to customers' homes just hours after they click the purchase button.

The public launch makes Google's once-exclusive service available to everyone who wants same-day delivery from San Francisco to San Jose, and signals that the Internet company may have found the formula to solve one of the most challenging problems in retail.... The cost is $5 for each store pickup.

...Shopping Express started last year as an experiment on Google’s Mountain View campus, and little by little, over the last six months, the company added members of the public to test the service....