Google has started offering search boxes within their search results. In the example above, a search box is offered for Amazon. The new service seems to be restricted to larger sites with a slant towards retails sites. Borders, BestBuy and OfficeMax offer the secondary box, as does a search for Wikipedia and The NY Times.
On the surface it would appear to be yet another dilution of Google’s famed simple interface, the very interface that helped put Google where it is today. And yet, some my find it useful.
It's a quick way to search within a site, but aside from retailers like Best Buy and Amazon, we could only find secondary boxes for the New York Times. Note that typical of Google roll-outs, you'll have to wait for it to reach your data center.