The main menu icon is not very obvious becaus it is a meaningless icon (logo) and has no text. It needs a short bit of text to its right that says "menu" or "start". In the menu's properties/options, an option should exist to turn off the text, but the text should be on by default to make the menu more discoverable to new users. This has been discussed on the mailing list. See an example at. http://www.joetainment.com/Plone/MenuIcons.png (occasionally this link might not work. If it doesn't try again a few minutes later.)
An optional label (either below or to the right of the icon) sounds reasonable to me and should be trivial to add.
Ok, I added this to svn trunk. It's not quite as flexible as I'd like. I wanted it to be configurable to have it to the left, right, top, or bottom of the icon, but logistically that's a pain to get right, and I'm lazy. So it's just a boolean show/don't show on the text. When the panel is horizontal, it's displayed to the right of the icon, and when the panel is vertical, it's displayed underneath the icon. This also seems to make the panel get wider when it's vertical; probably should revisit this. Open a new bug if there are issues with the implementation.