I have been preoccupied, or out of range, in the week since this disaster occurred and so hadn't read up on it. But here, for anyone who doesn't know about it, is a source that establishes beyond question one crucial point about the accident, and points to informed discussions of the many other aspects that are for now unknowable.
The source is this long and extraordinarily detailed dispatch by Tim Vasquez, of Weather Graphics in Oklahoma. Vasquez is a meteorologist, and his post is full of "SKEW-T" charts and other arcana that make me nostalgic for the rituals of "weather planning" from my flying days. But even for those baffled by the details, his sequence of charts -- based on very ambitious matching of flight-track data with a variety of innovative weather re-creations -- make this fact clear: AF 447 was passing directly through a large and powerful tropical thunderstorm when it stopped transmitting data (and presumably crashed).
This is Vasquez's Figure 12, showing the plane's likely path through Vasquez's recreated radar model of the storm. He requests on his site that some other charts, including the very clarifying Figure 13, not be copied elsewhere, because they "represent too much original work." Fair enough. Check for yourself.
An emphasis on the weather as the proximate factor in the crash is important in deflecting attention from some early speculation about meteors, inherent wiring problems in the Airbus, and so on. But it leads to two other major areas of uncertainty, which might be resolved if the "black box" is recovered or might never be known for sure.
One is why the plane ended up inside the thunderstorm. Even big, powerful airliners do everything they can to avoid flying through thunderclouds. Radar problems? (Onboard radar gives a useful but imperfect view of oncoming weather.) Some other reason? No one knows now.
The other is how, exactly, the storm may have brought the plane down -- since most airliners survive such encounters, hard as they try to avoid them. Structural breakup, caused by extreme turbulence? (Imagine ocean liners or freighters having their hulls cracked by hitting huge waves in just the wrong way.) Devastating hail destroying the multiple "pitot tubes" -- the devices airplanes use to measure their airspeed, without which neither the autopilot nor the real pilots can function normally, in turn leading to catastrophic failure of guidance systems? Lightning doing damage in some unusual way, since airplanes are usually designed to withstand it? Some other factor? All this is now unknown. But the Vasquez site will point you toward as much extra discussion as you want. (For even more, the AF447 discussion thread here, on the generally entertaining Professional Pilots' Rumor Network, or PPRuNe.)
Thanks to Parker Donham for the Vasquez lead.