From the official site:

Yankees outfielder Bobby Abreu could miss two to three weeks with a strained right oblique muscle, freeing Spring Training at-bats for Melky Cabrera, but not free agent Bernie Williams. ...

Abreu left the Yankees' Spring Training complex without speaking to reporters. Injuries of this nature tend to be variable among players, but the consensus appears that Abreu may not be ready to bat in a Spring Training game until the exhibition schedule is half-complete.

"He had a significant oblique strain, and it could be timely," general manager Brian Cashman said. "I know Joe said two weeks, and I'll probably say three weeks. But we'll see. It could be one week."

Disappointing, but at least it happened now... rather than later. Hopefully the 2-3 week projection proves to be accurate.