Zappos.com and 6pm.com are sending out the "we got pwned, change your info" emails.
Not everybody can view them, however - if you're outside the US, then you have a good chance of seeing this:
Region locked infosec alerts? Uh, yeah I don't think that's the smartest thing I've ever seen. What if you're a customer of theirs but on the road, for example?
For now, you'll have to make do with these screenshots, or you can visit the 6pm.com site whose alert page is actually viewable (though the details of the hack may differ from whatever happened to Zappos).