Damon's shoulder problem is actually tendinitis. Hard to say how big a deal this is, but it's certainly worse than I thought. I love this line from the AP article: "His ailment is exactly the kind of issue New York owner George Steinbrenner was referring to when he spoke out against the Classic." Yes, that's right, his 8 plate appearances in the WBC gave him tendinitis.
Update: It's begun. According to New York Daily News, "Cashman said definitively that the injury happened while Damon was with Team USA."
Update 2: From the NYT: "Told of Damon's setback in Puerto Rico, the Yankees' Bernie Williams said, 'I better get my arm ready.'"