It is useful that Tim summarizes his position in this context, voted up.

My position, developed with no background in philosophy or meta-ethics whatsoever and thus likely to be error-riddled or misguided, is that I consider it an unsolved problem within physical materialism (specifically, within the context of moral anti-realism) how "meaning" (the meaning of life and/or the value of values) can be a coherent or possible concept.