Via Baseball America, the Pirates have released a number of failed prospects:

RHP Yoslan Herrera - The big prizewinner in Dave Littlefield's weird experiment with international talent. Most teams attempt to sign Latin American amateurs at a young age and move them through the farm system over a period of many years. But all that was way too slow-moving for a short-term thinker like Littlefield, who instead spent a couple million bucks on Herrera, a much older player, and got him to the big leagues within a couple years. Unfortunately, his limp 87-MPH fastball wasn't nearly good enough to complement his decent offspeed stuff, and now Herrera is gone after getting bombed in the bigs in 2008 and spending an uninspiring 2009 at Altoona and Indianapolis. By the way, check out this little anecdote about Herrera by WTM:

Surprised about Herrera, too, because he made some progress this year, although at his age there's no way he's going to be a major league pitcher.  There might have been more going on with him.  I was at a DH in Bowie this year and Herrera was up in the stands in the second game after pitching in the first game.  He was rooting loudly for Bowie, so I wondered what was going on.

RHP Tyler Herron - The Pirates signed Herron, a former top draft pick of the Cardinals, after St. Louis surprisingly released him earlier in 2009. He didn't pitch particularly well for Altoona, and his stuff there apparently was terrible. But he still has that first-round pedigree, he hasn't been tried much as a reliever, and he's not old; it's a little bit weird that he's now been released by two organizations. It could be that there's some personal thing going on here.

1B Kent Sakamoto

3B Eddie Prasch - Prasch was Littlefield's third-round pick in his hideous 2004 draft. Prasch showed some on-base skills as he crawled through the minors, but his power never developed.

3B Bobby Spain

3B Brett Willemburg

OF Butch Biela - This is a weird one. Biela hit very well as an 18-year-old in 2007, then got by with a .342 OBP at State College in 2008. The Pirates thought enough of him to start him at West Virginia in 2009, but he wound up with back with the Spikes, not hitting at all.

OF Justin Byler

OF Jason Delaney - Delaney, the Bucs' 12th-round pick in '05, showed flashes of real hitting ability in the minors, but since he was almost 23 when he was drafted, he was always very old for his levels. He doesn't have much defensive value and he never developed much home run power, and now he's 27.

OF Jared Keel - Keel has always hit well in the minors, but like Delaney he has always been a bit old for his levels. Also, as a 31st-round pick, the Bucs have probably never viewed him as much more than an organizational player; if they liked him they probably would have sent him to Altoona last year, given that he hit 20 homers at Lynchburg in 2008. 

The Pirates have also granted free agency to Denny Bautista.