the icons installed in
/usr/share/icons/{hicolor,locolor,gnome}/*/*/openofficeorg3*png don't
adhere to freedesktop.org's Icon Naming Specification [1]. They should
be named according to the mime types specified in
/usr/share/mime/packages/openoffice.org.xml:

application-vnd.oasis.opendocument.<subtype>.png

A simple:
ln -s /usr/share/icons/hicolor/16x16/mimetypes/openofficeorg3-oasis-text.png \
  
/usr/share/icons/hicolor/16x16/mimetypes/application-vnd.oasis.opendocument.text.png

shows that this "works" as expected and the icons get picked up e.g. in the
GtkFileChooser and KDE since icon themes are required to fall back to hicolor
if no other icon is available [2]:

| In order to have a place for third party applications to install their icons
| there should always exist a theme called "hicolor" [1]. The data for the
| hicolor theme is available for download at:
| http://www.freedesktop.org/software/icon-theme/. Implementations are required
| to look in the "hicolor" theme if an icon was not found in the current theme. 

Note that I have observed this in Debian's openoffice.org package but the
maintainer indicates that this might also affect the upstream source [3].
 -- Guido

[1] http://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html
[2] http://standards.freedesktop.org/icon-theme-spec/icon-theme-spec-latest.html
[3] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=512731