The Brewers have acquired Zack Greinke from the Royals. The Brewers give up outfielder Lorenzo Cain, shortstop Alcides Escobar, and prospects Jake Odorizzi and Jeremy Jeffress. The Brewers are also rumored to be getting another player from Kansas City's major league roster, possibly Yuniesky Betancourt. After this trade and the Marcum addition earlier this offseason, the Brewers look set up pretty well for a World Series run but in the process.
Update: Via MLBTR: Peter Gammons tweets that a PTBNL is going to KC instead of Jeffress. Milwaukee also gets $2 million in addition to Greinke and Betancourt.
UPDATE by Charlie: I love this from the Brewers' perspective. They give up some good young players, but no top prospects, in order to get a potentially Cy Young-caliber pitcher. I had been confused about what direction they would take this year, but I think really going for it like this is a reasonable - and highly entertaining - solution. (And by "top prospects," I meant really strong, A-grade prospects - I wasn't commenting on these guys' standing within the Brewers organization. Odorizzi could become a grade-A guy, but he's too young and too far away to be one yet.)