Maybe the junior developer does have a great idea tomorrow - the question is, will anyone listen to him? Or will his small voice not be heard in a big company? It's not that they lack people who have the potential to do great things, it's the size/culture, the organization itself, which in (most) large corporations stifles new ideas and creativity.

radical changes will flow top down not bottom up. at least not in any organization of yahoo!'s size.

If your business plan is "maybe one of us will turn out to be the next Steve Jobs," it may be better just to sell to MSFT ;)

Good one, but don't quit your day job.