Fraser Spiers is an accomplished Mac developer who is also developing for iPhone.

On his blog explaining his approach for developing Exposure, his iPhone application for managing photos with Flickr, he describes three mobile contexts for using an iPhone. The following is my summary and labels for these contexts.

1. Distracted Mobile

On the move and not really able to focus so the iPhone application needs to be really simple with large buttons.

2. Waiting

Waiting in line or otherwise delayed, with some time to focus but often standing up with only one hand available. The iPhone application can have more functionality but must have an easy interface.

3. Away

The person is away from their desk and is using the iPhone because it is inconvenient to bring a laptop but they have more time and are sitting so they can focus on more complex tasks. Ease of use is still important but the user wants more functionality so they don’t have to wait until they get back to the computer at their desk.

Fraser makes a compelling case that iPhone application developers need to be aware of these different use cases and decide which of these they are trying to support. It is also a means of categorizing iPhone applications by which use case they are most appropriate for. This is something that will be used in future application reviews.