UPDATE at 6:35 pm CT from Bruce Levine of ESPN Chicago:
The Chicago Cubs are trading Carlos Zambrano to the Miami Marlins, according to a source familiar with the situation.
The deal, which is pending physicals, requires the Cubs to pay $15 million of the $18 million owed Zambrano in 2012. Zambrano has a $19 million vesting option for 2013 if he finishes in the top four for the Cy Young Award.
The Cubs will receive veteran right-handed pitcher Chris Volstad.
We don't really know much right now about this report, so I'll just pass along the tweet from Ken Rosenthal of Fox Sports:
Salary relief is what I'd be hoping for in any Z to the Marlins deal. This sort of deal had been rumored ever since Ozzie Guillen, a close friend of Zambrano's, became manager of the Marlins; Big Z would seem to be a good fit for them, and though he does still have considerable talent, it's time for a change both for him and for the team.
What I'd want in return is primarily salary relief, though I assume the Marlins would send a prospect or two the Cubs' way. Or maybe Gaby Sanchez could be involved in a larger deal. We await further developments. I'll update this post if/when a trade is made official.