This report from the team trainer per Yahoo:
"It'll be some time within the next several weeks," O'Neal said. "If you've had casts, you've had significant atrophy where the muscles deteriorate. We've got to get his strength back before we can go into baseball activities. We are anticipating that taking somewhere between 10 days to two weeks... The X-rays showed significant healing. We can start trying to get the range of motion and strength back, try to get him moving back toward the field. I don't want people to think he's going to be walking out on the field in a week, because he's not. I hope we could get his strength back in a couple weeks." In other words, it could be two weeks before he even begins doing baseball activities and another week or two after that before he's ready to play again.
The bones may be strong, but it will take some time to regain the muscular strength in his wrist. Considering his health, work ethic, and the Cubs need to have him back on the field, I think Lee will be back quickly. I still think he could appear in the White Sox series at the end of June, but as far as effectiveness goes, I agree with previous posts looking for a strong post-All-Star break performance.
By the way, I think the ideas about Phil Nevin coming in because Lee is worse than people are admitting are totally false. The Cubs could've had much better, and Nevin can pinch hit, DH, and fill in for off days for Lee and ARam. They got him for a second basemen, of whom they had at least FOUR on the roster since signing Womack.
D. Lee: back by late June, effective by mid July after the All-Star Break. And I'm sticking to it.