EDIT: BBC is saying he may be OK: http://news.bbc.co.uk/2/hi/africa/8453321.stm
Nothing seems to be confirmed yet, but if true Nigeria could be in for a rough political transition.
Nigeria in crisis after president left ‘seriously brain-damaged’
Senior members of Nigeria’s political elite will hold emergency talks on Monday after President Umaru Yar’Adua was reported to have been left “seriously brain-damaged” following medical treatment in Saudi Arabia.
President Umaru Yar’Adua has not been seen or heard from since he flew to Saudi Arabia for treatment for a heart complaint seven weeks ago. His long absence has pushed Africa’s second-largest oil exporter to the brink of its most serious constitutional crisis since the end of 33 years of military rule in 1999.