Mike made another post on his blog (can you tell I like this guy's work?) and it prompted some thoughts. He notes that consciousness isn't special and I agree. In Magical Identity, I discuss at some length why consciousness isn't special. Consciousness is the apprehension of our activities and the application of a rational explanation for why those activities occur. It's basically a filtered awareness and explanation of what we do and why we do it.
That said, what makes consciousness important for magical work is the fact that we can experienced altered states of conscious awareness, and while consciousness is a ultimately a filter, it nonetheless is also what provides a sense of self-awareness and an ability to question and examine what we are doing.
Situating consciousness in the proper context is useful because then we know its limitations as well as what it can do within those limitations. That understanding allows us to apply it toward our magical processes at just the right place to use it effectively, while also enabling us to be skeptical of it, as it is ultimately a very subjective experience.