As of today the rules for links in posts have changed. The automatic parsing of links in the post editor has been disabled. What this means is, only links that are properly placed within the “URL” tags will be treated as links. All links that are not embedded in “URL” tags will from now on be treated as plain text (and therefore will not link to any other page).

The following isn't considered a link anymore: www.si-community.com
Placed in the proper URL tags: http://www.si-community.com