Take the folks at Walmart Labs (http://www.walmartlabs.com/ http://www.walmartlabs.com/) for instance, NodeJS hackers working on the backend powering Walmart's

Take the folks at Walmart Labs (http://www.walmartlabs.com/ http://www.walmartlabs.com/) for instance, NodeJS hackers working on the backend powering Walmart's mobile commerce. A small percentage of hackers will get a chance to work on problems and devise solutions at the sort scale they work on. You certainly won't see similar challenges if you limit your scope to companies with less than 50 people and less than 10 million in funding. Unless you are a founder or maybe a first hire that would seem to preclude you from almost any interesting company coming out of SV in the last 15 or so years.