Just an update, Mac4Lin SVN has been updated with a new version of GTK Themes' and GTK Icons' directories. They are compatible with the latest version of GNOME and distributions like Ubuntu, Fedora etc.
To download everything goto this page: http://mac4lin.svn.sourceforge.net/viewvc/mac4lin/
and on the botton click on "Download Tarball". If you however want to download specific components (like GTK_Theme etc.) then goto that directory and download the specific tarball. To install, you can follow any guide available online to install either the GTK theme or the GTK Icon theme.
I am yet to make a formal release, but those who want to experiment with the latest version and file bugs are welcome to do so