I assumed that READ posts such as those containing a subject like "what bike are you riding" were given that status because the question was asked so many times. I know that at least in the MTB forum, as soon as a thread like this dropped down on the list, another person would ask the same thing, starting a new thread about the same thing that everybody replied to again. I assumed that it was to keep the same idea from coming up in a new thread every week. By making it a READ thread, no one asks it again and people have a single place always at the top of the list to post such things. Might be wrong, but thats what I figured...
-Moab