Google UK states that to gain higher rankings in its index, your website requires links from other high quality websites. The UK SEO community is in agreement that this will remain the case for the foreseeable future in 2009. see Google and Links.
Link Building Strategy
Link building strategies fall broadly into three categories: see implementing a link building campaign
SEO based Links that combine to achieve higher Google rankings
Links that bring relevant traffic and revenue
Links that form part of an overall network of client websites and funnel traffic into the main corporate website . see global intranet