The deal is officially done. You can consider this the overflow.
I like this move, mostly in that there's no reason to dislike it. Putting aside the one percent chance that Aaron Baker becomes a good major-league power hitter here, the Pirates gave up nothing of value. Baker's strikeouts and general problems hitting for average (although he has improved this year in that regard) make him a longshot to be much more than AAAA fodder.
Derrek Lee is nothing special at this stage, obviously, but he's a functional big-league ballplayer in a position where the Pirates didn't have one. I'd like to see the Pirates hunt for upgrades tomorrow, and I'm sure they will. In other words, I'd have a problem if Neal Huntington said, "We got Derrek Lee! We're done!" But they might not find another deal they like, and for whatever reason, their timing is terrible. They've been sellers all these years where it's been a buyer's market, and now they're buyers, and teams have gone back to trading top prospects again. They can't really do what Philadelphia did to get Hunter Pence, or anything crazy like that. Their prospects have too much value for them, since prospects are cost-controlled and their payroll simply can't be half of what Philadelphia's is now or in the immediate future. They've done well, in this market, to get something for very little.
Someone like Baker is exactly the type I was hoping the Pirates would trade - good enough to have value in this kind of move, but not nearly good enough that the Pirates are likely to regret it in the future.