This article on big companies and innovation – Microsoft’s creative destruction , explains why there is so little innovation at the largest companies in the world. Big companies are able to attract the best and brightest talent in the world, but usually there is so much office politics, that the best ideas are rarely converted into workable products.
If a large amount of investment required, large companies have a distinct advantage, but in terms of new ideas for low investment products/services, a smaller business can be better that a manager in a big company as they can spend time more productively. Not every idea works out, and few managers wish to put their career at stake if it does not.