Sixth-round pick Tyler Eppler, a RHP, and 18th-rounder Erik Lunde, a second baseman, have reportedly agreed to terms. The report at Pirates Prospects adds that other picks are expected to sign shortly. No doubt many will be college seniors, as is Lunde. Eppler is a junior.
UPDATE by Charlie: Here's my writeup on Eppler, a big righty out of Sam Houston State. Lunde is not only a college senior (out of Lander University in South Carolina), he's also small at 5-foot-9; you hate to judge a guy without knowing that much about him, but Lunde's age, draft round and size are fairly clear indicators that he'll be an organizational player.
UPDATE by WTM: As noted by znc1 in the comments, Chris Cotillo has tweeted that the Pirates have agreed to terms with their top pick, SS Cole Tucker for a $1.8M bonus. The slot for the pick is $1.9255.