Siri has been out since 2010 on the app store. Is there any reason (other than Apple's push with building it into the operating system) that users will take more notice of it now than they have in the last (nearly) two years?
Integrating it with the OS is the reason users will take more notice now. I'm not sure why you dismiss that, but it's actually a huge deal.
I've used Siri on and off since it came out. It's pretty good. The reasons I don't use it more are precisely the problems that will be solved by integrating it into the OS. First, the app was a pain in the ass to activate, requiring half a dozen taps to get started. This problem disappears on the 4S. Second, the app couldn't do anything with the data on the phone (like send e-mails or check my calendar) because it didn't have access, or at least they didn't build it to. Again, this problem disappears with integration.
The main advantage of something like Siri is convenience and speed. The app couldn't achieve that precisely because it was an app that wasn't built in to the OS.
I'm not disputing that bulding it into the OS is a big deal, but pointing out that in its 2 years of public release on the app store, Siri didn't see the organic growth of apps like Instagram or Hipstamatic.
Apple has added new features to integrate it more deeply with things like the Calendar and Reminders apps, but at the same time, half of Scott Forstall's demo commands at the 4S keynote were exactly the same as the Siri demo at 2009's All Things D conference.
A big part of building it into the OS is that it only takes a single action to activate, instead of the half dozen or so plus a considerable amount of waiting that it takes to activate the standalone app. I believe this will result in a qualitative difference. The app was mostly a novelty that was usually slower and less convenient than doing things directly. The OS service is likely to be considerably faster and more convenient than the other paths that exist for achieving what it can do.
This is vastly more capable and polished than the app in the App Store for the last two years. Deep integration with calendar, reminders, location (it looks like they've smoothed over a lot of the awkward permission requests in iOS 4), phone book and hardware (via the home button) makes it a radically different app.
From the videos I've seen it looks like it launches via holding down the home key and at least for some command separation you need to hit the "talk" button with the Siri application.
There are two options to activate Siri: use the Home button, or just put it to your ear, as if you were talking on your phone rather than to. The second option can be disabled, but it's there and enabled by default.
"The secret to ending all poverty and hunger has been hidden deep in the earth's crust for two decades. Is there any reason why digging it out and placing it in Times Square for all to examine (except for the fact that now everyone can see it) will cause people to take more notice now than they did before?"
It was a diamond in the rough, it just got de-roughed and as such is more diamond-y. Or it was a really cool product that people over looked, by featuring it prominently Apple hopes to get a lot of reward for very little effort.
