General feeling at the moment is that she died from alcohol withdrawl, something called the DT's "delirium tremens" which can be fatal.
Sauce amoungst many others.
"Whether alcohol withdrawal is the culprit in Winehouse's case remains to be seen, but it is certainly a possibility. Doctor Carol Cooper tells the Sun that the sudden shock of withdrawal could have led to a seizure so violent that it caused her death.
"The heaviest drinkers have a particularly severe form of alcohol withdrawal called delirium tremens, or DTs," says Cooper. "They may fall into a stupor and sleep it off, or lapse into a coma -- or have dangerous seizures."
Although I don't condone her previous lifestyle I do feel, if the above is the true cause of her death, some admiration for her effort to give it all up. That being said, she should have heeded advice from a medical professional as to the way in which she should have kicked her habits.