An idea for an APP

I saw something on the amusing/disturbing border yesterday.  Walking towards the train station I passed a tram stop where an earnest young person (earplugs firmly in place) was engrossed in fixing their playlist on the iPhone.  The person was clearly waiting for a tram, which arrived, deposited passengers, waited a moment for the person to look up and then moved on.  Is this a situation you have found yourself in before?  Perhaps you've witnessed similar scenes.

Anyway, I've spent 24 hours or more turning this over in my mind.  There's a side of me that's always open to ranting about how technology makes people do dumb things, but I don't think that would do more than keep the diminishing number of readers here amused for thirty seconds or so.  There's also a side of me that would unfold a grand philosophical shrug of the shoulders, but that wouldn't be quite as entertaining.

Instead, here's a challenge.  Given that the iPhone is here to stay, couldn't someone design an application that would allow people to get on with their multitasking without missing public transport?  Perhaps something that interrupts anything else that's running to alert the user to the imminent arrival of a tram.  I imagine an application like this could make use of the real-time tracking that Yarra Trams has introduced across the tram network.  Who's up for a challenge?