Not for the one I'm seeing. When I hover over the new posts icon, the one that has two speech balloons, the hover-over says "New Posts." It says the same thing when I hover over the icon I'm talking about.
FWIW, the icon I see looks like you take the "New Posts" icon, replace the right speech ballon with a pencil, and make the whole icon greyscale. I really only ever see it on the "Kegging and Bottling" category.
I did find on the Simple Machines Forum online manual that you can get to such an icon summary page, but only as an admin: http://wiki.simplemachines.org/smf/Smileys_and_Message_Icons
I"m not at all worried about any of this; it has just piqued my interest. I assume the pencil signifies something about authorship or editing, and since I've only ever seen it on that one category, perhaps I started a topic but never posted it or something and the forum thinks it is still hanging out there.