It seems pretty clear that Dwight is not happy in L.A. Dwight is from Atlanta and friends with Josh Smith. Thus, he might be willing to sign there long term, but there are no guarantees that he or Smith will come back so it would be a risk for Atlanta to say the least. But I think this trade would be a good trade for both teams.
ATL - Dwight, Metta
LAL - Horford, Korver, Petro
LA gets a talented younger player on reasonable deal in Horford, gets a much better shooting SF in Korver and saves about 6 million in salary this year and a lot more in the future.
Atlanta gets Dwight, which if he can stay healthy would make them a real threat to Miami this year (especially with metta annoying Lebron all game), and gets about a half a year to convince him and Smith to stay.
Given Dwight's contract situation I can't see LA doing much better than Horford and Atlanta seems like one of the few teams that would bring on Dwight for value without assurances he signs long term.