I posted my addon to the nUI HUD Design downloads section. This addon allows you to see your targets Level up in the HUD. So you don't have to look down at the Unit Frames for this information. If you look at the screen shot in the addons section you can see where he Level is displayed.
It is also colored by the Units level relative to your own, thanks to Scott's wonderful work.
http://www.wowinterface.com/download...rgetLevel.html