From:http://angelicpenguins.blogspot.com/2006/07/add-new-sled-menu-to-ubuntu.html
The latest contribution to GNOME by Novell has been the menu overhaul known as ‘SLAB’ in their upcoming commercial distribution SLED. If you want to try it out you don’t have to download and install the SLED pre-release you can add it to Ubuntu. Just like XGL, SLAB is open source.

First we need to take care of some dependencies. Open your terminal and type this (all one line):
sudo apt-get install libgnome-desktop-dev libpanel-applet2-dev libgtop2-dev libdbus-glib-1-dev network-manager-dev libhal-storage-dev libiw-dev libgnome-menu-dev libresmgr-dev libavahi-core-dev banshee f-spot mono
Next download and install this .deb file made by cbudden here.
Then download and install slab.schemas.zip and extract it to your Desktop and do this in your terminal:
cd ~/Desktop gconftool --install-schema-file=slab.schemas
Now when you right-click on your panel up top and choose ‘add to panel’ you will notice that in the ‘Miscellaneous’ section there is an option called ‘Main Menu’… this is the one-button SLAB menu. You will also notice that there is now a control panel for Ubuntu. Right-click on programs and ‘add to favorites’ or drag and drop to modify it.
I played around with my panels a little but my top panel still seems so bare!

If you want to check out the cvs source and try to compile it:
cvs -z3 -d :pserver:anonymous@anoncvs.gnome.org:/cvs/gnome login (hit enter for password) cvs -z3 -d:pserver:anonymous@anoncvs.gnome.org:/cvs/gnome co -P slab
Thanks to the SLAB thread in the Ubuntu forums.