Aside from the things mentioned in the video (offline by default, fully customizable UI, <browser> tag etc) one of the most interesting things about this is the

Aside from the things mentioned in the video (offline by default, fully customizable UI, <browser> tag etc) one of the most interesting things about this is the change to application architecture that makes Chrome apps mirror traditional native apps in an important way - the View is no longer the instance. A challenge for a variety of apps built using the traditional web container is that the view is the instance. This poses challenges for apps that are mostly invisible, like chat apps. The main challenge is sharing live state between running instances. You can attempt to share state between views you open via script but when the user inadvertently launches another instance by clicking a link or typing a view all bets are off. With this new system, your app has a background page that acts as the app's instance - the entry point and core event receiver, it is effectively ever-present (or can be woken by events) and can manage the app's various views. I think this is an important and useful development that will allow a new class of apps to be more easily built using web technologies.