Earlier in this thread (post #18) I voiced my concerns regarding the medium term danger to the stability of Sudan in particular, and the Horn in general, having more to do with the much more formidable SPLA than the problems in Darfur. The North’s failure to make progress with the boundary commission, and various other outstanding differences, seems to be exposing cracks already:-

Sudan's southern rebels walk out
http://news.bbc.co.uk/2/hi/africa/7039616.stm

The BBC title refers to them as rebels but they are constitutionally a major part of the government and it is difficult to see how the the president remains any legitimacy without their inclusion.