Belfiore said that the Windows Phone app catalog, a carryover from WP7, has grown to more than 120,000 items -- but the new OS, he explained, isn't just about app volume. It's also about attempting to use apps in new ways.
One aspect involves Live Tiles, which have been upgraded to allow pinning apps. The result is an interface that evolves dynamically based on apps that the user chooses. In other words, the tiles can be configured to automatically display up-to-the minute content from a given app, or even from profiles that friends and families build within apps. "The idea," Belfiore stated, "is that you can find the things you care about -- the particular people you care about -- and put them right up front and center in your experience."
Tweets, status updates and more will appear not only when the phone is actively engaged but also through the lock screen. Rather than being confined to single static image, it is now a fluid display that presents new information as it comes in. "It's more personal ... the ultimate glance-able UI," Belfiore said, reiterating the event's primary theme.
The apps themselves, meanwhile, are not merely ports from the previous OS. Microsoft has forged partnerships with app makers to develop new versions that are optimized for the WP8 interface. Examples from the event included new editions of Facebook and Skype, an iteration of the Urbanspoon app that will respond to voice queries, and -- in the announcement that drew the biggest response from those in attendance -- a new version of the Pandora app that will arrive in early 2013, and which will offer WP8 users a year of ad-free music.
Belfiore said the Microsoft ecosystem will soon include 46 of the top 50 apps available on other mobile phone platforms. He also remarked that the company's SDK, which had not previously been available to all interested developers, would be released for free Tuesday.