Voice leading, as I understand it, is a way to anticipate the changes in any given chord progression, and this theory is applicable to all genres of music. It relates to the intervals between the notes you are playing in succession.
In country and bluegrass for example, we engage in voice leading without even knowing it. For example, the last measure of a tag ending will often be two beats of the V chord followed by the I chord. This is voice leading because say we're playing in the Key of G, the V chord (D) contains an F# (the third of the D major scale), this third is the 7th in the G major scale. So hearing that F# is anticipating the next chord which is your I chord, which is of course G. There is a half step away from F# to G.. so hearing the F# makes you anticipate the resolution to G.
Does that make sense?
In jazz, you need to think about this when you are improvising solos. It's not hard once you break it down and understand theory. I still need to explore this concept in detail.