Peavy For Zambrano?

Phil Rogers of The Chicago Tribune says that there is some buzz regarding a Second City swap of Jake Peavy and Carlos Zambrano:

"Some baseball people believe the White Sox could have interest in the Cubs' Carlos Zambrano, possibly even for the newly acquired Jake Peavy.  It would be a way for two teams without much money to spend to shake things up, but wouldn't Peavy have more value than Zambrano at this point?"

Peavy, as you may remember, listed the Cubs as a team he was willing to be traded to when the Padres first looked to move him.  Zambrano has solid numbers for the year, posting an ERA of 3.69 and 8 strikeouts per 9 innings. 

With just two starts in black and white, people are already wondering if Peavy will be a part of the team's 2010 plans.  Big Z has had a very strong September (2.81 ERA, 38 K's in 32 IP) but frustrations on the north side of Chicago have put every Cubbie under the gun.

Starting in 2010, the continuation of Peavy's contract will pay him $52MM over three years plus a club option.  Zambrano will earn $53.75MM in the next three years with a vesting player option for 2013 worth $19.25MM.

Could an intra-city trade of this magnitude ever happen?  Should either team pursue such a trade or is this simply a case of the grass being greener on the other end of the Windy City?