As Jeff Taylor and a bevy of Reason readers have observed, Ghazi Kanaan, Syria's interior minister, is said to have committed suicide. Perhaps he did, though to me that seems unlikely; having amassed tens, if not hundreds, of millions of dollars during his long tenure as Syrian proconsul in Lebanon, he had the option of eventually spending part of that sum in exchange for giving information to the United Nations commission investigating Rafik Hariri's murder. Kanaan and Hariri happened to enjoy good relations, and I would guess Kanaan opposed his assassination, though he certainly knew who was involved.
What made Kanaan dangerous was that he was a well-connected and wealthy officer from the ruling Alawite community; if anybody could combine the intelligence networks, communal ties and money needed to replace the Assads and their kin in a coup, it was he. That possibility, and the fact that Kanaan might have been willing to give information on the Hariri murder to the U.N. investigators, perhaps in order to advance his chances of removing the regime, may have doomed him. Still, at this stage there is no evidence of a coup being prepared, so that one should consider alternatives.
One Arabic newspaper, Kuwait's Al-Siyassah (which supports the Kanaan coup thesis), says that Kanaan was going to be made a scapegoat for the Hariri murder by the Assads, alongside three other intelligence officials (including Kanaan's successor as intelligence chief in Lebanon). The alleged "suicide" allows people to suggest he killed himself because he feared being accused by the U.N.–implying guilt. In that sense his demise was designed to avoid his publicly denying this, and proving it. No one will ever know.
However, one thing is certain: the Syrian regime is unraveling, and while the Assads might be able to count on the fears of their Alawite coreligionists to keep a handle on power for a time, the fact that a senior Alawite is now dead suggests the community is not as united as was presumed. It also indicates that Syria was involved in Hariri's murder, something Assad has repeatedly denied. That's the regime's dilemma: on the one hand it has professed its innocence in Hariri's killing; on the other, it must prepare for a U.N. report that might blame Syria by finding scapegoats, which contradicts the claims of innocence.
(I had written about Kanaan and how Syria ruled Lebanon for Slate back in May 2003. Read today it makes an amusing memento mori.)
Addendum: For a round-up of views on the Kanaan affair, and observations of his own, Tony Badran at Across the Bay has posted this; he highlights the fact that Kanaan may have prepared for his grand departure by talking to a Lebanese radio station, a very rare occurence by Syrian officials. Josh Landis at Syria Comment also offers some perspectives.