I am not sure what you did or why, but Unity is in the repositories. Once
installed it will say Ubuntu Netbook Edition in the Session Menu. You can
also install Unity 2D, but you need to add a PPA to your repository.

www.ubuntugeek.com/...ty-in-ubuntu-10-0410-10.html
www.techienote.com/.../...-unity-2d-on-ubuntu.html

If you want to try it as it is in 11.04, then your best bet is to do it in a
VM. However, you can only get the 2D version to work because Compiz requires
more than 128 MBs of graphics memory and VirtualBox can only give that as a
maximum. I have heard that VB 4.04 allows Ubuntu 11.04 to work but have not
tried it.

You can get it by installing testdrive. Add the ppa first then install
testdrive. You need Virtualbox to run the virtual machine. Testdrive is
really a Natty appliance set to run in a VM.
https://launchpad.net/~testdrive/+archive/ppa