This article highlights the importance of intuitive and well-designed navigation in terms of the usability of a mobile application. The article describes several useful design guidelines regarding navigation to be kept in mind when designing mobile applications. Perhaps one of the most important is that menu item labels should accurately describe their functions. Users should not have to guess what action will result from selecting an option. The labelling of the option should make this clear. The provision of an exit function on every screen is also very important, as it allows users to always have an "emergency exit". Navigation design should also ensure that sensitive menu options such as "Save" are not placed directly next to an "Exit" option, as users may then accidentally exit instead of saving.
The article provides several useful tips that would benefit the usability of any mobile application.
The following link provides a range of good information regarding designing the navigation of mobile applications for the Series 60 platform in particular (Select Usability Guidelines) -> Navigation: Forum Nokia library