Not a hologram exactly, but on Strictly Come Dancing's results show last night (the missus was watching and I just happened to be in the room ok *ahem*), Barry Manilow did a "duet" with Louis Armstrong on "What A Wonderful World". Which was creepy enough ... and it brought back to mind Pat Metheny's thoughts on Kenny G doing the same, see http://www.jazzoasis.com/methenyonkennyg.htm (which can be tempered slightly with PM's own follow-up at http://www.jazzguitar.com/features/kennyg2.html)