I think anyone expecting to get any value in trades at the deadline is kidding themselves. Other than Byrd, no one on this team who the Cubs would want to trade that would bring back anything better than the next Jeff Stevens. Even the guys that could bring back some value if the Cubs paid part of their contract (specifically Dempster & Zambrano) are probably guys the Cubs would prefer to keep.
I'm sure they'll deal some guys, but it will be unproductive. They'll get 2-3 AAAA guys for Fukudome, Johnson, and maybe Grabow. They'll give someone like LaHair or Smith or Colvin 100-150 AB, which will prove nothing. And they'll still fill all their needs (3B, 1B, maybe OF) through free agency and trades in the offseason.
Bottom line, this trade deadline is not going to be worth getting worked up over unless the Cubs really turn it around and become buyers instead of sellers.