What's new is that we have added a counter for the posts and you can see subtags of a concept when pointing on the latter. Also, usually in those cases where the linked page would contain no posts at all, the link is hidden.
Let me show you how it works by using an example. The search for 'linux' as a concept yields this sidebar. (Here you can find a reminder of what concepts and relations are.) Note that the counter is only visible when the user is logged in. Here, there is no link to the user-tag page, because the user 'ak' does not have any posts tagged with 'linux'. Neither does this user have a relation where 'linux' is the supertag, so the link to the user's concept page is hidden, too.
Of course, you can search for more than one keyword. As an example, consider the search for both 'mathematics' AND 'algebra' as tags, which yields the following sidebar. The search term is split up into the single keywords and for each one there is a link to the corresponding concept page (if the result set is not empty) and there is one link for the whole search term (although this query might yield zero posts). You may expect a reference 'algebra as concept from ak', but like in the previous example, the user 'ak' has no relation in which 'algebra' is the supertag, so this link does not appear.