Valve ****** up, no update from official Steam sources (like the website, or twitter, etc.)
No apology.
Threat of doxing, SWATting by using the info leaked. Identity theft, pizza delivery scams, blah blah blah.
They posted on their blog about it at 1pm on Sunday, I believe. Possibly Monday.
The configuration change was in response to a ddos attack. They're currently contacting everyone it happened to. If you weren't online when it happened, then you couldn't have been hit.