10:51pm: The Orioles announced the deal.
Baker, 23, has a .285/.353/.474 line with 15 homers in Class A Bradenton this year. The 2009 draft pick did not crack Baseball America's preseason list of the Pirates' top 30 prospects.
10:07pm: The Pirates are "very likely" to acquire Lee tonight, according to Dejan Kovacevic of the Pittsburgh Tribune-Review (on Twitter).
9:40pm: It doesn't appear that the Pirates will have to take on much salary, according to Rob Biertempfel of the Pittsburgh Tribune-Review (on Twitter).
9:07pm: The Orioles will obtain a Class A hitter, Connolly reports (on Twitter).
8:57pm: The Pirates are "getting very close" to acquiring Lee, according to Dan Connolly of the Baltimore Sun (Twitter links). A deal is "very likely," Connolly reports. The Orioles are likely to send cash to Pittsburgh and obtain a Class A player.
4:54pm: The Orioles are looking to move Derrek Lee as soon as they can, mostly for salary relief, according to MLB.com's Jenifer Langosch (on Twitter). The first baseman left in the eighth inning of this afternoon's game and is not in the lineup for the second half of today's double-header, Dan Connolly of the Baltimore Sun reports (on Twitter).
The 35-year-old has a .248/.306/.409 line in 360 plate appearances this year and earns $7.25MM. His play has improved in July, however; he has a .261/.306/.533 line with six homers this month. Lee, who was dealt to the Braves last August, would be an August trade candidate if the Orioles don't move him this weekend, as there's a good chance his salary would clear waivers.
Though his contract expires after the season, Lee doesn't project as a ranked free agent, so he probably won't be tied to draft pick compensation. The Pirates inquired on Lee and the D'Backs could also be a fit.