Caltech neuroscientist Christof Koch is interviewed by The Scientist this week on his decade long discussion with Francis Crick about the nature of consciousness: 

Koch states that he and Crick have revised their earlier proposition that synchronous neuronal oscillations might be at the heart of consciousness. They originally believed that this theory might be the solution to the so-called binding problem: How do differently processed aspects of an object bind together into one percept--red + round + shiny = apple, for example. "Unfortunately, the evidence is slim for a direct relationship," Koch says. "What's much more plausible now is that synchronized firing activity in the 40-Hz range may be necessary to resolve competition (among separate neural circuits competing for conscious attention)... There's quite a bit of evidence that oscillations might be involved in biasing the selection, but once I'm fully conscious of [the percept], it's unclear whether [the oscillations are really needed.]"

As visual scientists, Koch and Crick are primarily defining consciousness as differences in visual attentiveness.  Although this reductionist approach may be moving the ball forward a bit, consciousness will remain an elusive concept for years to come.