Recent　experimental　developments　have　brought　into　focus　optomechanical　systems　containing　multiple　optical　and　mechanical　modes　interacting　with　each　other.　Examples　include　a　setup　with　a　movable　membrane　between　two　end-mirrors　and　＂optomechanical　crystal＂　devices　that　support　localized　optical　and　mechanical　modes　in　a　photonic　crystal　type　structure.　We　discuss　how　mechanical　driving　of　such　structures　results　in　coherent　photon　transfer　between　optical　modes,　and　how　the　physics　of　Landau-Zener-Stueckelberg　oscillations　arises　in　this　context.　Another　area　where　multiple　modes　are　involved　are　hybrid　systems.　There,　we　review　the　recent　proposal　of　a　single　atom　whose　mechanical　motion　is　coupled　to　a　membrane　via　the　light　field.　This　is　a　special　case　of　the　general　principle　of　cavity-mediated　mechanical　coupling.　Such　a　setup　would　allow　the　well-developed　tools　of　atomic　physics　to　be　employed　to　access　the　quantum　state　of　the　＇macroscopic＇　mechanical　mode　of　the　membrane.　(C)　2011　Academie　des　sciences.　Published　by　Elsevier　Masson　SAS.　All　rights　reserved.