If you're looking for a wrap-up of today's iPhone press conference, the simplest and smartest explanation I've found is from Brian Lam at The Wirecutter, who goes through the new features and describes why they matter. Maybe I don't really need a service to send people greeting cards through my phone, but even though the new iPhone looks like the one I already have, it is faster, holds more MP3's I'll forget to listen to, has a better camera, and has a voice activated assistant, which seems cool:
The iPhone 4s is Your New Voice-Controlled Assistant: Apple's 4s has a voice control system. Like Kitt in Knight Rider. Supposedly, you're going to be able to ask it a question and get an answer or make your phone do things. What can you ask it? I don't know! But Siri (that's her/its name), for starters can be asked What the weather is like. And to read you your messages. And to find you restaurants. Greek restaurants, even, if you want to get tricky about it. And it will tell you! You can also ask it to set calendar appointments. It can pull info from wiki, wolfram alpha (the super science-y search engine) and other places. You can shout at it to play the song you want, like a DJ that listens. You can make it send emails for you. And the engine powering Siri can work with built-in apps, but as Jason Snell from Macworld notes, this would be bad ass if any app could use voice control.
How This Will Change Your Life: This is really astounding computer science. But, honestly, if we all start talking into our phones in public like they are our personal assistants, its going to get really weird, really fast. There's no mainstream precedent for this kind of behavior. But I think this sort of system is going to keep people from texting and driving right off the bat. I have to stop doing this, myself. Confession: Once I played an entire game of Words With Friends on a drive to Lake Tahoe. That was bad. Sorry.