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brotherhood_of_LAN - 2:29 pm on Jan 16, 2008 (gmt 0)
Google could also get a fair idea of market penetration regarding adwords by having a comprehensive list of UK businesses; by having physical and web addresses to reference.
Yell's site is not very SEO friendly and I'm sure Google see more potential in presenting the information in another way, particularly since they show Yell results in Google local alongside a map.