The media model may very well be a good one to compare them to, as they are both reliant on creative vision and talent. The creative corporate culture is superb for attracting bright minds and Googleplex is a perfect laboratory/playground for creating the google magic. The organisational process of allowing all employees to use 20% of the work time combined with the small teamwork style appears to be a good formula for generating prototypes that, if found of value, can then be developed more fully from alpha to beta.
The only limitations I can see is the possibility of ego getting in the way of doing great work and the size of the company eventually turning employees and customers off the company. This could very well be a branding challenge for Google in the near future of how to deal with growing into a big corporation.