We were pretty sure the next iPhone was going to pack some awesome new voice command tech, but it's being demoed live, and living up to expectations: talk to it like a human, get results from a smart person.
The things the Siri can tell you are diverse and will be incredibly helpful. And because it uses natural language instead of awkward preset commands, you can speak to it like a person, not a program. It'll do the interpreting for you. Just hold the home button down and speak away. Ask what the weather's like, and it'll bring up a report. Ask it for a word definition, and it'll bring it up via Wolfram Alpha. Siri can bring up local restaurants, ranked by rating, search the web, read you your notifications (great while driving!), and set wakeup alarms at your command. Oh! And it'll write your texts and emails for you, like a diligent little secretary.
Siri's even GPS-powered, giving you location-based reminders of your own creation. For instance, ask Siri for a reminder not to leave your keys at work, and it'll ping you when you leave your office radius. All this voice-crunching comes at a cost, however—it'll require the extra horsepower of the 4S' A5 chip. It will, however, learn your voice as you jabber on—so Siri can only get more accurate as you use it, with support for English, French, and German.