Editor’s note: New devices, new experiences and new demands on usability change all the rules. Alfred DeRose provides a useful checklist developers can follow to deliver exceptional usability at every step in the ‘app flow.’

Usability – and how shortcomings in device/software features and functionality are impacting the mobile space at all levels – was the focus last week. Around the world (and in Prague, where Tego Interactive is headquartered) professionals and practitioners came together at World Usability Day 2009 to exchange views and seek solutions to the fundamental usability issues that threaten to stunt market growth and stifle innovation, if we ignore the work to be done.