What's the real number? Who knows? Both lists contain names of players who have announced retirements: Gabe Kapler, Troy Percival, Brad Radke, Steve Karsay, Joe Randa, and Vinny Castilla. Some players have gone off to Japan such as Jason Johnson, Jared Fernandez, and Lance Carter.
MLB.com's list has a lot of minor league free agents on it which explains most of the discrepancy.
Interestingly, MLB.com lists Barry Bonds and J.D. Drew as "signed" while the AP does not.
The World Series champion Cardinals have apparently given up on four players: Ronnie Belliad, Jose Vizcaino, Jeff Weaver, and Preston Wilson. It does appear that Wilson finagled a trip to the White House. Check one row up from George Bush and then go over three people to the right. Is that Wilson standing next to Scott Spiezio?
The Cubs appear to be the only team that has no players who went into free agency who are still unsigned. That's because the 2006 Cubs were just that good. The demand for them was high, see for yourself!