Nothing, really it has NOTHING to do with meego, i mean it can be meego UI, but this UI is not developed by meego devs. It's one of the common linux DEs and i use it at home for several years already. If it is really the DE they would use by default in meego on desktops(laptops or netbooks) you can see more screenshots here - http://www.xfce.org/about/screenshots
be careful i don't know if xfce4 would be really used as default DE, i assumed it from other user post in this thread