Wolfram Alpha is a great knowledge tool, it uses semantic searching of data sources to give some pretty great results. Wolfram Alpha is also the power box behind Siri, the Apple Voice Assistant (note: in my opinion it is not a personal assistant yet, but nor is S Voice).
Indeed, it seems in updates to the S Voice app on the Samsung S3 and Galaxy Note that the Wolfram engine references are built in and are functional. At this point neither Samsung nor Wolfram have said whether this will be available on other devices such as the S2 or Galaxy Tab. This move is clearly a levelling exercise for Samsung against Apple – but on testing (for a few hours) it appears that Google Now still comes out on top of all three, this is subjective but an interesting outcome. Siri is ranked second to me, and S Voice still lacking but moving up… watch this space for a full review and test.