I was impressed that most of these searches already work on regular google search (just tried them). I had no idea the knowledge graph could do those already. This is not only a great demo of android voice search. It's a great demo of google search.
"How much is Angelina Jolie worth?" is throwing an answer: https://www.google.com/search?q=how+much+is+angelina+jolie+w... But "How much is Brad Pitt worth?" isn't: https://www.google.com/search?q=how%20much%20is%20brad%20pit...?
"Fish species in Lake Tahoe": https://www.google.com/search?q=fish%20species%20in%20lake%2... But "fish species in mississippi river": https://www.google.com/search?q=fish%20species%20in%20missis...
Edit: changed ".es" by ".com" in all the links.