Open innovation is claimed to be the new breed of innovation requiring enterprises to look beyond the boundaries of their organisation and to use external and internal actors and knowledge to successfully create value. In related business management literature, shifts from closed to open models are argued to be triggered by new technological, economic and social trends so that many organisations (at least partially) virtualise, their members being distributed across different locations and embedded in various socio-economic and cultural contexts. Complementing that line of argument, the current paper undertakes socio-systems-theoretical revisits to key institutional premises assumed in concepts above organisation, knowledge, collaboration, complexity etc. - to examine, explore and restate in which sense 'openness' may be feasible in organisational realm and with what respects 'open innovation' may be supported, accordingly. It is argued that, rather than requiring to tear down organisational walls 'outwards' (which in principle is not possible), 'open innovation' enables, and is enabled by, differentiating organisations 'inwards' to better turn 'irritations' feared into chances recognised to leverage upon.