Just tweeted from KC Johnson:
Now, as speculated earlier in the week, trading for a signed Hinrich would make sense as it means the Bulls wouldn't have to use a cap exception to sign him. The Bulls would also receive a trade exception for the difference in Hinrich and Korver's contracts (presumably, $2m).
Trading Korver instead of waiving him on Sunday means the Bulls are off the hook for the $500k guarantee Korver is owed. It's possible that the Bulls are sending cash to cover this for Atlanta, but either way that wouldn't affect the Bulls' ultra-tight cap situation.
In the big-picture, team-on-the-court sense, this is still super cheapo stuff by the Bulls, but I give them credit for using, as Mark Deeks would say, 'creative financing' in this situation once they chose to go this route.