Didn't we just have version 2.0 a couple weeks ago? Yes we did.
Matt Cutts explained that 2.0 was targeting specifically spammy sites, while 3.0 targets more spammy queries. So the algorithm looks more at the query versus looking at the site. You are smart SEOs, so you can figure out what that means.
Matt also explained that version 2.0 also added some negative SEO factors, to reduce the amount of negative SEO that can happen. If you believe that.
I do not believe this launched just yet, it may launch today sometime, or maybe tomorrow - but likely today, Matt Cutts said. Based on the lack of complaints in the black hat forums, I do not think it launched at the time I am writing this.
Reminder, this will look specifically spammy queries, such as terms like [payday loans], [casinos], [viagra] and other forms of highly spammy queries.
Update: It began rolling out 4:40pm EST:
@BtotheMcG it's rolling out now!— Matt Cutts (@mattcutts) June 12, 2014