This happens on http://musicbrainz.org/release/e7fe61ca-65b8-4abb-8723-1e7c1a5e0a49/cover-art
Would you be satisfied with something in the vein of "All artwork displayed on this tab provided by the Cover Art Archive" or "These images provided by the Cover Art Archive"?
Whatever makes it clear that the sidebar image is not provided by the CAA is fine.
Let's rephrase the question then: Do either of Ian's suggestions make it clear to you that the sidebar image is not provided by the CAA?
The latter phrase seems fine to me, but I'd be happy with either.
nikki: Yes, both of them make it clear to me.