Recently Google Webspam head Matt Cutts released an video about Paid links. As you all knows that Google is known for its non-tolerance for paid links to a website. People are making a trend to gain high qualities links by paid seats but from now Google discontinues this trick. Thus Now Google delivers a penalty to such a website that has paid backlinks. Note- Ad Sponsorship is different thing and buying paid links is different. So lets watch a complete video from Matt Cutts.
Matt Cutts Video on Paid Links: