Peek is part of a deeper UI paradigm in BlackBerry 10 called Flow, which is designed for single-handed use, controlled mainly by your thumb. In Flow, you don't switch among apps through a home screen -- though you do have a home screen to launch apps when desired -- but instead thumb through active apps and services by thumbing through them.
The Peek feature lets you use a thumb gesture to reveal alerts and updates in your current apps, such as seeing what new emails have come in while reading a specific email. The Cover approach has the BlackBerry Hub at its base level, which aggregates all your status and messages in one place. You can always peek at the Hub to see what's new globally, and then switch back to what you were doing. And you can open the Hub and use it as a launching point for whatever update is of interest.
The BlackBerry 10 UI is highly tuned to "hyperactive" users who want to quickly check on what's new without interrupting their main focus, said Vivek Bhardwaj, RIM's head of software portfolio. It's an approach modeled on the common BlackBerry users' behavior of keeping the BlackBerry in view under a table while in meetings while the user surreptitiously remains connected. That behavior relies on being able to hold the device in one hand and navigate it through the same hand's thumb, which is why the Cover UI and functions like Peak use thumb-based gestures.
Bhardwaj also said the UI favors communication-style activities that have long formed the backbone of what people use a BlackBerry for, compared to the more general-purpose iOS and Android, where individual apps are the focus and you manipulate them with one hand while holding the device in another. He said that this orientation to the dominant psychographic segment of the BlackBerry user base should both appeal to the 80 million current BlackBerry subscribers and provide a meaningful UI differentiation from iOS and Android.
BlackBerry 10's accommodations for multiple development options -- including native C++, HTML5, recompiled Android, and Adobe AIR -- is also a boon. "If there was any move that was going to save them, it was to have a real-time OS like QNX underneath everything they did that had tool chains for all the different approaches that people like to program in," said Dennis Gearon, co-founder of Kwince. "I have to say I'm absolutely amazed that they supported already as many platforms as they do."