The talk by Ajit Jaokar was really an eye-opener for me. Widgets are key.
The iPhone is usually perceived as a closed system. There is no SDK, so application developers can not add new things to it. It is true, but the question is whether this hampers the functional broadness of the device.
One might see the inclusion of the Safari web-browser as the inclusion of a widget management system. Each widget that can be accessed through the browser adds a new application to the device. And each application adds new functionality.
It is not as good as a real application, but will probably suffice for many users. I guess it will become easy to access (and save?) widgets. It will not be as good as real applications, it will less integrated, but probably will do very well for now.
How much widget management this browser will offer is also interesting to see. Can widgets be cached? Can I create bookmarks for each widget? Can I create an app icon for each widget promoting it to app level? Many interesting questions.