One of the sideshows of Cannes is which celebrities can be wrangled into attending by agencies. This year's crop is varied. Havas scored not just Kofi Annan but also Bob Geldof . Grey is bringing E-Street Band and Sopranos vet Steven Van Zandt . Young & Rubicam has Who frontman Roger Daltrey . The glitter is nice, but the real interest should be in two guys who are arguably the most powerful forces in shaping the future of advertising, and who will also be there: Microsoft CEO Steve Ballmer and Google CEO Eric Schmidt. Ballmer is giving a seminar about online advertising  and being honored as the Media Person of the Year, while Schmidt is having a sit-down conversation with Publicis CEO Maurice Lévy .
—Posted by Brian Morrissey