Wolfram recently announced the feature in a blog post on their website:
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.
So how do you make it work? It’s simple – just tell Siri “Wolfram iPad 2” or “Wolfram Seagate hard drive” and Siri will quickly search Best Buy’s database and return prices and descriptions.
It doesn’t work very well at the moment, often returning strange results, but it does show some serious potential uses for Siri.