@goafrit- I'll agree with you that the two CEO thing has had checkered results in the past. But I don't see a transition to Chi-Foon as sole CEO that quickly. I'll take Aart at his word that he's not planning on going anywhere right now. I'll cast my lot with analyst Rich Valera, who said that this move paves the way for Chi-Foon to be the sole CEO, but not for quite some time. It's not like Aart is on the outs with the board (of which he is chair) or the investors, and it's not like there is likely to be some kind of power struggle between the two men.
I read this as a formalization of a succession plan that was already basically in place. And I wouldn't be surprised if what prompted them to go with co-CEO route now is that Chi-Foon was drawing interest from another company or companies about a CEO job.
Congrats Chi-Foo. This is the move to become the sole CEO within the next 2 quarters. This co-CEO does not work. It failed in BlackBerry, Goldman Sachs and I am sure it will not be long Chi-Foo takes over.