As WebmasterWorld & Search Engine Watch Forums member, glengara, points out in a thread named "Spam is an Arms Race" - Douglas Merrill/Google, the BBC News featured an article on link spam today.
The article is named Google to stay focused on search but it has a number of mentions of search spam. Here are some quotes;
"Spam is an arms race," said Mr Merrill, adding it was a multi-million dollar industry which was trying to fool search engines.
Unlike spam e-mail, web spam tries to trick search engines into featuring websites selling products such as drugs high up on a list of search results.
The spammers exploit the way search engines work by bombarding blogs and comments pages with links to their websites.
Google prioritises websites in their search results if a particular page is linked to by other sites.
Mr Merrill said: "Spammers are highly motivated. There is a lot of money at stake."