IMHO, Zen uncertainty is something quite different than infinite uncertainty. The definition referenced by jstultz is "Zen Uncertainty: Attempts to understand uncertainty are mere illusions; there is only suffering."
However, a completely Zen-equivalent definition would be:
Zen Uncertainty: Attempts to understand certainty are mere illusions; there is only happiness.
It is actually quite easy to understand Zen from a mathematical standpoint -- Straight lines are merely large circles. That is, positive infinity is equal to negative infinity. Therefore, Zen uncertainty means that infinite uncertainty is equivalent to infinite certainty. Not exactly what jstultz had in mind!
Before dismissing this idea out-of-hand, consider two things. 1) There is no mathematical inconsistency inherent in believing this. 2) Scientific experiment shows this to be the case in reality.
Mathematically, note Robinson's non-standard analysis and his hyperreal numbers. There is nothing in mathematics, other than definitions, that prevents equating negative infinity with positive infinity.
For a physics example, consider negative Kelvin temperatures, specifically nuclear spin systems. The cooling thermodynamic temperature profile of one such nuclear spin system experiment was (See, IIRC, the Purcell and Pound reference in the article.):
room-temperature ----> +4K ----> (0K) ----> -4K ----> (-infinity == +infinity) ----> room-temperature