UPDATE: Lou Piniella confirmed today that the goal is to return Zambrano to the rotation. "We're going to stretch him out to get back in the rotation and we'll see when he's ready," Piniella said. Tom Gorzelanny could be the odd man out (or is a trade in the works?).
Yesterday, Lou Piniella announced that Carlos Zambrano will be moved from his setup role to long relief. Asked if Zambrano would rejoin the rotation, Piniella said "Down the road, if need be."
If you read between the lines, it certainly looks like the Cubs are going to try to stretch out Zambrano in order to move him back to the rotation, basically admitting they made a mistake. Zambrano has gone 0-1 with a 6.23 ERA in his 8 appearances in the setup role.
Although he has said all the right things since the move was announced, you could just tell by watching him that his heart (or head) was not into it.
In any case, my guess is that the Cubs will try to find a way to get him back into the rotation by early-to-mid June. Its possible that they want him back in the rotation so that they can showcase him for a potential trade. However, with his hefty price tag and no-trade clause, trading him will not be easy.