Satya's blog - Domain keys

I got a few gmail emails today, which had domain key signature headers. Wondering what that is, I did a google search and found this:
http://antispam.yahoo.com/domainkeys

which seems to be a signed analog of SPF. Hmm, they changed the name or I'm looking at the wrong web site. It used to be Sender Permitted From.

And I just saw the word qmail as a link in google search results. It seems that the words gmail and qmail are hard to tell apart in certain fonts, when underlined, due to the descender being obscured.