The entire survival of Yahoo under a specific business model was staked to this. At the time -- this was my first job out of college -- I didn't care at all about those aspects, but the technical learnings for me (primordial NoSQL data stores, software-based high availability, hugely distributed architecture spanning many continents, what later came to be known as "devops" practice, etc...) were immense.
Ah. Has there ever been a Yahoo project that had more hype?