I am not sure anything of substance is being accomplished here. The Brazilians were looking for someont to surrender to before, to get a meal and a bed for a night, I suppose, now they are not. That's all this is saying. The "success" of the change seems to be the reduction in workload. When this fence is finished deportation should be across the fence regardless of origin. Plane tickets to Rio ain't cheap. Let Mexico deal with them. When Mexico starts building a large population of South Americans in Northern Mexico, then Mexico will start dealing with the problem.
Based on Senater Coburn's statements and his attempt to influence the Senate Judiciary Committee's negotiated immigration reform bill, it would appear that expedited removal of the OTMs is not a roaring success. It is not clear, at least to me, how punishing the un-cooperative nations will lead to more expedited removal of the OTMs.
This is supported by Sec Chertoff's recent statements that catch and release will not be fully implemented until Oct 06, when Congress may, or may not, fund a sizable number of new detention beds.