The search box appears when someone enters the name of certain Web addresses or company names — say, “Best Buy” — rather than entering a request like “cellphones.” The results of the search are almost all individual company pages. Google tops those results with a link to the home page of the Web site in question, adds another search box, and offers users the chance to let Google search for certain things within that site.You can see what they're talking about here. However, if you actually type a term into the new box, the results page reveals that the search being performed is one that has been available for years: "site:url.com term."
Some companies are up in arms:
Um . . . guys? It's true that most people don't know to use the "site:" operator, but it's not a big secret either.
“Eventually this could be a huge problem if Google starts throwing this out there to all brands,” said Pinny Gniwisch, vice president for marketing of Ice.com, an online jeweler. Mr. Gniwisch ... said Google’s new feature did not appear when users searched for Ice.com, but he said he would object if it did. “This is essentially giving the customer a way to leave a search for your site,” he said. ...
[One internet consultant said] "For our larger clients, we’ll probably ask Google to turn this off.” That is the route that Amazon has apparently chosen. The retailer declined to comment for this article, but last week Google’s search-within-search function did not appear when users entered “amazon.com” into the initial search box.