As nolok mentioned, the blocking in Chrome takes place on the client side. We're looking at adding block links to Google's search results along with server-side

As nolok mentioned, the blocking in Chrome takes place on the client side. We're looking at adding block links to Google's search results along with server-side code (which would let your blocks work on any computer you logged in on, for example), but that code takes longer to write and test than the Chrome extension.