From Rotoworld:
A bone scan detected no damage in Kerry Wood's arm, but the Cubs have decided to shut him down for a week due to triceps tendinitis.
Wood will need an additional week or two to be ready for game action, so a return in the second week of June seems to be what the Cubs are aiming for. However, another mild setback would probably result in Wood needing a rehab assignment, pushing his return back to the end of the month.
Cubs can't catch any breaks but I think Dusty Baker is to blame for this one.