UPDATE (19/1/11): The pattern library has been moved to a new home at design4mobile.com (site no longer exists), but has not yet been made available. Other resources that might be useful include Nokia’s Design Pattern library and Jennifer Tidwell’s IxDA talk about the topic.
Little Springs Design has started publishing design patterns for mobile devices (primarily targetting mobile phones for both web and native applications). So far,
six twelve have been published.
“Keypresses should be kept to a minimum for common actions. Unlike a desktop, a keypress is not simply a mouse click, but the number of times the cursor has to be moved to get to a command, then the command itself. For a Gmail message, for example, getting to “Archive” or “Next Message” can be ten or more keypresses. Numbered access allows that to be one keypress, although it is restricted to users who choose to learn more about the application. On the other hand, numbers do not harm usability by novices and indeed provide visual cues that certain commands are somehow different.”
Link: UI design patterns (design4mobile.com, site no longer exists)