Siri - What Else It Does

Siri can also do calendar scheduling, send messages, etc., all verbally.  Instantly provide currency exchange rates.  

Can search Wikipedia by asking Siri for info.  

Siri alone is going to be justification to get the new iPhone 4S.  

Siri also does dictation so you can write emails by voice.  

Built-in with support for English, French & German.  Will add more services and languages over time.