Google Guy's take on the useless backlink command, Here is a small snippet taken from the original posting by him in search engine watch forums

Google doesn't return all backlinks in response to a link: command. In the ancient days, it was because there was a finite amount of storage space on the machines that served link: requests. So we only kept the backlinks for the top N pages. Later as we moved to a different indexing system, we kept backlinks for the top M% of pages. This was helpful for important pages, but it meant that Mom and Pop sites with lower PageRank wouldn't have as good a chance to see their backlinks.

source: forums.searchenginewatch.com/showthread.php?t=2423&page=2

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