[ Thanks to kiterunner for this link.
]
“As we have already seen in the post on What’s new in
Ubuntu 10.04 ‘Lucid Lynx’, the theme change is a among the major
updates going to happen in Ubuntu Lucid 10.04. New theme will have
new color schemes which is going to set it apart from all other
releases of Ubuntu till date. This is because Ubuntu is undergoing
a complete branding makeover and new themes should be seen in that
light. Here is a step by step howto on installing these new
Radiance and Ambiance themes in Ubuntu Karmic,
Jaunty.”