This came up on icefaces.org (still visible on the live site as of March 12/08).
ice:menuItem appears to render two links sometimes, such as:

<a href="../community/contribute.iface"/>
 <div>
  <a href="../community/contribute.iface">
   Contribute
  </a>
 </div>

In the case of the site, we get a blank white menu entry. Initially the menus were generated dynamically, with embedded loops similar to:

c:forEach
 menuBar
  menuItem
   c:forEach
    more menuItem

Various different approaches were used try to get around the problem. ice:panelSeries, ice:dataTable, ui:repeat, less menuItem elements, using ice:menuItems directly, using f:subview, moving forms around, moving includes around, adding or removing IDs, and so on.

In the end a static page was used (ie: the menuItem elements are hardcoded directly on the page), and although less common the problem is still visible (again, see the live site).

The problem does not happen locally, so perhaps it is a threading issue or some sort of problem with the rendering order. Regardless, the app can be reviewed on http://lnstage1.ice/main/ and associated source is under /repo/applications/icefaces.org/project (specifically WEB-INF/inc-plugins/header.jspx).