While Ubuntu's Unity interface has come a long way since it made its full-on debut a year ago, it's still not desirable to everyone. Likewise, GNOME 3.x is maturing, but not everyone is happy there with the radical changes from the GNOME 2.x desktop that many have become to know and love.
There's the MATE Desktop attempt that's a fork of GNOME2 packages and it hopes to live on, but its future has already been called into jeopardy. Another more popular alternative for those that feel their desktop doesn't get along with Unity or the GNOME 3.x Shell is the Cinnamon desktop as a fork of the GNOME Shell and Mutter, etc. Cinnamon at least is receiving more of a following and garnering a fair amount of attention for at least the time being. There's also of course LXDE, Xfce, KDE, and others for those wanting something else out of their Linux desktop.
The proposal for the "Precise Pangolin" release of Ubuntu is to do something slightly different with the desktop. Jo-Erlend Schinstad has brought forward a new concept with not being satisfied with Unity, the GNOME Shell, or the GNOME 3.x fall-back mode. Effectively he just wants to see indicator-applet-complete re-added into the Precise repository and a new package that changes the default configuration and behavior of the GNOME Shell fall-back mode.
What Schinstad would like to see is adding the indicator-applet-complete to the Ubuntu universe repository (a PPA is currently available), an "ubuntu-classic" meta package, and possibly alter the "press-and-hold-alt-to-customize" behavior. The ubuntu-classic meta package would change the default configuration of the GNOME Shell fallback mode, include the correct panel layout that also makes use of the indicator-panel-complete, and rebrand the GNOME fallback mode as being "Ubuntu Classic" within the LightDM log-in manager.
The mailing list message with limited discussion thus far can be found on the ubuntu-desktop list.
Meanwhile, there's a more vibrant discussion within the hat-wearing camp about bringing Ubuntu's Unity as a new desktop option to Fedora. That discussion can be found here.
Unity and the Ayatana components have already been made available as packages within the land of openSUSE, Frugalware, and Arch Linux, but it's not found in many distributions beyond that. When Unity was still quite young there was some discussion about bringing over the Canonical-sponsored desktop at that point as an option within the Fedora repository, but that ultimately never took off.
Already brought up in this latest discussion is some incompatibility issues between the upstream GTK+ / GNOME packages used by Fedora and what the Unity desktop expects in terms of its menu and other portions of the API. Jef Spaleta has been attacking this effort, among others. At the moment it looks like any port of Unity to Fedora would be unofficial and not welcome within the Fedora repository until using upstream dependencies/APIs.