I was going to question why a mid-level team like Chicago would deal cap space for two players that make them better, but not contenders, but looking at the cap numbers, it actually makes some sense.
The Bulls lose Drew Gooden's expiring contract, but even though Brad Miller is due to make more than $12 million next year, he comes off the books after that - in time for the monster 2010 free agent class. The other key player in the deal, John Salmons, is actually quite reasonably priced at around $5.5 million a year for the next three.
Chicago also loses Jerome James/Tim Thomas (the flat tires they acquired in today's Larry Hughes' dump) after 2009-10 as well.
So the Bulls have boosted their chances this season, albeit marginally, and they haven't damaged their long term prospects much.
I assume Joakim Noah will lose a few minutes as a result of the Miller/Gooden swap, and Salmons will cut into Ben Gordon and Luol Deng's minutes at the swing spots. In fact, the 1-3 position just got pretty crowded with Hinrich/Derrick Rose at 1/2, Gordon/Salmons at the 2, and Deng/Salmons at the 3.
The big winners in this trade, are of course, Spencer Hawes and maybe Francisco Garcia of the Kings (it depends what Andrea Nocioni's role is).