Based on a "directive" from Jimmy Wales [1], the English version of Wikipedia has started using the "nofollow" tag on all external links (the foreign language versions had been doing that for a while). That tag tells search engines to not pass any "search engine juice" (e.g., PageRank) from the WP page to the linked page. While sites that have links in WP will continue to receive visitors from those links, they will (supposedly) not receive search engine-related benefits (they might, however, be spidered by some engines). Certainly, some search engines may special-case WP (including having...