Obligatory jwz quote: ``Zawinski's law of software envelopment''
Every program attempts to expand until it can read mail. Those programs which cannot so expand are replaced by ones which can.
(obviously Myspace did not read mail ;-))
[EDIT]
In response to http://news.ycombinator.com/user?id=patrickaljord below, Myspace introduced email service in mid-2009. Perhaps the above should read, ``(obviously Myspace did not read mail back then when it mattered ;-))''