According to ESPN's Jorge Arangure (insider-only; summary from BuccoFans here), the Pirates have signed 17-year-old outfielder Willy Garcia to a $280,000 bonus.
This is confirmed at the Dominican Prospect League website, where you can also see a picture of Garcia.
This signing is the first I know of by the Pirates this year in which the bonus figure has been reported; it may or may not be the largest. A couple weeks ago I questioned whether, since the Pirates had not signed Miguel Sano or any other Latin amateur to a big-ticket bonus, they had at least signed some players to mid-level bonuses in line with the ones they gave Exicardo Cayonez ($400,000), Jordaneli Carvajal ($350,000) and Jonathan Barrios ($250,000) in 2008. This one certainly falls into that category.
UDPATE: Johnny Cuff points out in the comments that Arangure also reported a couple weeks back that shortstop Ramses Pena signed with the Bucs for $150,000.
UPDATE 10:49 PM: Neal Huntington denies this is totally done.