[IanMikutel]

The talk is that they have deeply integrated Wolfram Alpha to automatically pull and handle queries like the one you mentioned.

Source: http://www.appleinsider.com/articles/11/09/30/mockups_demons...

[BrainScraps]

I knew Wolfram would be involved with handling these queries - especially when that demo had the "How many calories are in a banana?" line !

[newhouseb]

Siri actually already does this (for example ask it "How old is steve jobs?" or to do any math for you)