Thanks Dardo. I was a little surprised that none of the usual suspects had this appearance listed. I went ahead and sent Karim the info for Santanamigos around the time I posted it here, but the album isn't on discogs either. It is on Spotify (and iTunes and Amazon as I mentioned), but they don't have the typical "featuring" link which would make it show up on Carlos' page.
And again it's weird that the only mention of it from the Santana machine was that posting by Carlos basically saying "this is a great record. You should hear it" with no mention of the fact that he'd played on it.