Have you done even a minimal amount of homework to see if this question has been asked before? Here are a few discussions:

* http://news.ycombinator.com/item?id=4058492

* http://news.ycombinator.com/item?id=3251877

* http://news.ycombinator.com/item?id=3703024

The question has been discussed several times:

http://www.hnsearch.com/search#request/all&q=title%3A%28...