Google & Bing Have Whitelists – “Exception Lists”

Google has long maintained that "the algorithm" is what controls rankings, except for sites which are manually demoted for spamming, getting hacked, delivering spyware, and so on.
At the SMX conference it was revealed that Google uses white listing:

Google are now block any Sites from Serch Results

Google announced you can now hide or block certain sites from showing up in the Google search results.

When you do a search in Google, the search results will show a new link near the “Cache” link when you click a result and then return to Google. The link that Google adds to the search results reads “Block all example.com results.” Clicking on that will allow you to block the site from showing up in the Google results.

Google Algorithm Changes will help pure sites to come up

There has been quite a bit of noise about last week's 'farmer update' announced by Google. In a nutshell, the latest algorithm change aims the sights firmly at low quality sites that offer no unique content.