Only 12 seconds off from magic digits!!
>>>5550555
You make it cool.
a) Students – both cool factor and because students tend to be more readily early adopters of that sort of shit (e.g. e-mail in mid-90s)
b) Celebs – because now suddenly it's like you have an intimate pipeline to your fave celebs. Could you have imagined that 20 years ago?? And even more so now with the twatter.
Once you get a critical mass on board, the rest follows easily.
Of course the opposite can also happen (as MySpace demonstrates).