How about "What is the complete list of films made by Orson Welles"?
How about "What are Google's search results for 'Orson Welles filmography'?"
C'mon, you think I didn't try all those :-)
Until I get home (and can fire up Mathematica) I'm not sure how to do such symbolic queries. It's not Deep Thought - I feel like getting the most benefit from it would require some kind of Regex. Might be me. They haven't put the FAQs or tutorials up yet.
I do feel a lean towards computable rather than retrievable data, if that makes sense. I just started with that example as something I knew about that seemed to typify the popular imagination of how it might be used.
Like I say, I'm still finding out how to parse queries effectively, particularly for comparison data...in between working (cough).