We've recently finished the sound design for this iPad app's functionality.
Phaidon create high end coffee table books and have taken their 'Design Classics' edition, a collection of 1000 items over 300 years of design, and put it into a new iPad application.
The sound design had to represent the level of craftsmanship and quality of the product design contained within. Condiment Junkie looked to the world of precision watch making as a source for the sounds.
Adding sound to the functions and navigation of apps makes them more tactile and engaging, and can also help to communicate the design, content, and the brand identity in a more immediate way. People have also learnt, through film and tv, that these types of technology will sound a certain way in the future. The future is here, and it should sound how we expect it to.