Siri

Something I had noticed during Scott Forstall’s Siri demonstration:

Where most designers would have placed a loading… bar, pinwheel icon, or other progress indicator, Siri maintains a casual, conversational flow, peppered with interjections and non-lexical disfluencies.

This accomplishes two things: it allows the phone to complete what is likely to be a data or processor-intensive task — speech-to-text translation, interpretation and query generation; and, more importantly, it personalizes and humanizes the software.

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Update:

Another example, provided by @morrick.