Specialized search engine Wolfram Alpha, one of Apple's launch partners for Siri, has partnered with Best Buy to deliver shopping results. As a result, iPhone 4S users can now search a number of products and categories from Best Buy's catalog, and get prices and descriptions returned.
From Wolfram Alpha's blog post announcing the feature:
Just in time for the holidays, we’re introducing a new functionality that provides consumers with a unique approach to shopping. By leveraging data from Best Buy’s public APIs, Wolfram|Alpha users will now be able to browse more than 35,000 appliances and consumer electronics products. Wolfram|Alpha’s intuitive natural-language interface helps you hone in on the precise products you need, while its powerful data visualization capabilities give you an innovative overview of any shopping category.
Simply ask Siri "wolfram iPhone 4S" or "wolfram samsung television" and it quickly returns Best Buy shopping results. It's certainly not the easiest way to search Best Buy's website and occasionally returns fairly useless results, but it is another example of the potential uses for the Siri's contextual voice recognition technology.