Been wanting to post this for a while - heard in a presentation at NESTA/ Steve Moore's Reboot Britain event earlier in the year. I forget who said it - I think it was Charles Leadbeater - but it has stuck in the brain:
Culture eats strategy for breakfast
In other words, however clever your vision, however fine your organisational structure, whatever your methodology, if the people aren't with you, don't get on and/or can't be bothered, forget it. Very true!