the driver knee airbag rattle is fairly common, I had it and it bugged the hell out of me. VW messed me around so i fixed it myself with bits of foam carefully placed.
I've also had the rear view mirror, sun visor, a-pillar and seat beat adjuster rattles, all successfully (touch wood) fixed with anti-rattle felt or foam/sponge.
My latest which has appeared is the bottom of the front doors where the speaker is, buzzing like crazy over virtually all surfaces.