Hi edhotmail ... have a look at the
CAGED lesson I posted here a while back. What it shows are all the chord tones for C major. If you were to improvise over a plain old C major chord, all those notes would be the strongest to use as the main melody notes of your improvisation. That's not to say that you would stick exclusively to them (unless you wanted to) but they're the strongest.
The principle I have just described is how most jazz players approach melody. So it's not scales so much as chord tones that they use to create their melodic phrase. In the case of C, you're playing around with just 3 (1-3-5); if the chord were C9th, however, you'd have 5 to play around with (1-3-5-b7-9), so you can see that jazz, which uses a lot of extended chords, is a rich source of chord tones, since each chord in the progression presents a new array of possibilities.
Have a look at two lessons of mine:
The Power of Chord Tones
The Power of Chord Tones 2
You should see and hear in these that this approach works. Of course, since chords come from scales, you could first learn all the scales/modes, figure out which belong with which chords, eliminate the non-chord tones mentally from the patterns and have the same batches of notes to choose from, but why waste all that mental energy? Since you need to know the chords anyway, why not just leave it at that? You'll learn all those scales and modes by default via the chords.
The trick is being able to see chords as fretboard-long arrays of notes. As daunting as that may sound, it's not that hard to do. You just need to know how to look at the fretboard.