The Mac menubar for GNOME/Xfce is a gtk2/gnome/xfce application that mimics the look and feel of a Mac-style menubar.
It's important to note that this is not just one app, but actually consists of 3 pieces of mutually-dependent software. These include a patch for gtk2 (2.10.x and 2.8.x), a gnome panel applet, and an xfce panel plugin (for 4.4+ only).
The sources for this software package are hosted on AUR (Arch User Repository), and the packages are gtk2-aqd, gnome-macmenu-applet, and xfce4-macmenu-plugin. Additionally, there is an xfce plugin that emulates round panel corners: xfce4-corner-plugin.
If you're interested in installing this software, the home page provides a link to an Ubuntu HOWTO for installing the patches and applets. There are also binaries available for Ubuntu Edgy and Arch Linux.
To use this software, you will need GTK+ version 2.8.x, which is a requirement that should be noted. This latest release includes the ability to use ~/.macmenu-tslist for application title substitutes, with a default list being created the first time modification is detected automatically.
Overall, the Mac menubar for GNOME/Xfce is a great option if you prefer the Mac-style menubar and are looking for a software package that provides this feature. It is easy to install and use, and with the latest release, it includes a useful new feature that enhances its functionality.
Version 1.0.14: N/A