Small companys have an advantage, but the potential influence of a large organisation suggests that there's a great benefit in size if you can effectively overcome the natural tendency toward stagnation through a tree structure.

I think technology can certainly help an organisation work effectively together with weaker integration, but ultimately a huge portion of it will be culture and personality.

Developing effective technology that assists in the development of the right sort of culture for a fluid, large organisation would be an interesting challenge. I think it might address the same sort of things that 'team building' exercises and retreats usually spectacularly fail at.