Who's Leading Al Qaeda?

Strategypage tells of a new terrorist video which is raising interesting questions about the status of Osama Bin Laden:

In the video, Dadullah is shown making the usual Taliban anti-infidel pitch. At one point he refers to Osama bin-Laden, using the words, “sitting beside me.” There is then a clip of bin-Laden, who says a few appropriately belligerent words. The monitor then cuts back to Dudullah, who continues his diatribe. The video, which apparently has not yet seen wide circulation, has reportedly provoked a good deal of attention from intelligence specialists.
...Intelligence analysts specializing in Al-Qaeda... suggest that the video may be a clumsy attempt to send a “signal” that the terrorist leader is still very much in charge of operations.

I've been wonding why we haven't heard from"boss" Bin Laden lately. Now I'm still unsure.