It would be very foolish, but I do wonder if they used Hadoop to compare their hashes with publicly exposed hashes after breaches of other sites (for example, Gawker or Zappos) in order to force reset affected users.
Apparently this breach is a year old, so nothing to do with it. Maybe they just decided to go public today hoping that focus would remain on LNKD or (even better) people would just think "ah well, it can happen to everybody".
