Starting yesterday, the Compiz based Unity is available in a PPA (ppa:unity/ppa) for Ubuntu 11.04 Natty Narwhal. Unity can be enabled on the Desktop version (you don't have to login to the Ubuntu Netbook Edition) from the CompizConfig Settings Manager (Unity is a Compiz plugin):
After enabling the Unity plugin, the first obvious change is that the Unity launcher becomes transparent:
However, there are still some issues with the Compiz based Unity (that's why it's only available in a PPA for now): Dash doesn't work so to launch applications you can only use the Unity launcher ("dock"). Also, the icons in the upper panel are aligned to the left for some reason.
Since Unity now uses Compiz, you can enable any plugin:
Add the Compiz Based Unity PPA in Ubuntu 11.04 Natty
The brave who run Natty already can install the Compiz based Unity using the following PPA:
sudo add-apt-repository ppa:unity/ppa
sudo apt-get update
sudo apt-get install unity
Also install CompizConfig Settings Manager
sudo apt-get install compizconfig-settings-manager
Info and the last 2 screenshots thanks to mogorvamormota.hu as I couldn't get the Compiz based Unity to work in a virtual machine.