The problem with the intrapreneurship idea is that it's really hard to beat desperation as a motivator. I have seen people behave very differently in the context of a startup vs a corporate research lab thanks to this dynamic. Some people thrive in the corporate R&D environment, but the innovator's dilemma eventually gets to their managers.
Cisco has done a great job balancing this, actually - they keep contact with engineers who leave to do startups, and then acquire their companies if they become successful enough to prove the product.
