There are some major questions that have to be answered about the Tunguska event before any definitive claims can be made. Some of them are:
(I'm referencing the article you linked to, Vince)

Why was there atmospheric activity (lights, etc) preceding the event, dwindling away quickly afterwards? A space object could hardly have effects before it encountered the earth.

What could explain the magnetic storm that apparently ensued?

Why is there no significant debris? I know the arguments about comets, finely dispersed particles, etc, but they seem to be ad hoc. Particles found in the trees of the area can be explained by fluctuations in on-going space dust depositions.

How are the different paths described by eye-witnesses explained? (and there seem to be many consistent reports that indicate two or more "flight paths", different in altitude, direction and even time) Explanations invoking "non-ballistic" trajectories seem verging on the flying saucer fringe.

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As far as I can determine, the explosive power of the event has been estimated by the size of the forest blow-down and the seismic activity noted right afterwards. The power estimation assumes an explosion at fairly high altitude (because that is where an space object, had it been the cause, would have exploded?), and if some mechanism closer to the ground were involved, much lower powers would be required to produce the observed effects. Also, seismic activity could be involved as a cause rather than an effect of the event.

All the information I've seen on the Net about Tunguska seems vague and inconclusive. If anyone has links to more definitive sites, I'd really appreciate them.