In a Monday afternoon briefing, Stephen Wolfram spoke about the direction of Siri and Wolfram Alpha integration. He explained that over time, the range of queries that users can ask Siri that are served by Wolfram Alpha continues to get broader. This is apparently a natural byproduct of using a cloud-based system with the Siri API.
Wolfram stated that Siri queries are generally easy for the service to process. "Spoken queries [have] a different character from typed queries," he explained. "People are a lot less lazy in what they say than what they type." When users type, they put things into a natural shorthand. In spoken requests, they naturally fill in those missing pieces.
The verbal noise likes "ums" and "ahs" are apparently easy to remove, while the extra spoken context words allow better translation to Alpha queries.
Wolfram said he looks forward to deeper and broader developments with Siri.