This is really true, and something we are experiencing now in the company I am working for. Traditionally we've been a company with ~12 employees, small project

This is really true, and something we are experiencing now in the company I am working for. Traditionally we've been a company with ~12 employees, small project teams of 1-4 people. Now the company has expanded to over 40 employees over two offices, with team sizes becoming larger than 10 people. We have experienced the exact difficulties you have described, and have been slowly adjusting to create just enough structure to organize and motivate people. I would add that an additional area that becomes more important as a company grows is communication. Once the company gets past the size where the CEO/Director is getting around and talking with each employee on a weekly basis, and physical walls start to grow between teams, communication becomes much more difficult in both a vertical and horizontal sense (a side effect of added hierarchical structure i suppose?).