I think the best such rebrand in recent history has to be AOL:
Old: http://nuzumcl.files.wordpress.com/2009/03/aol-logo.jpg
New: http://www.bizmology.com/wp/wp-content/uploads/2011/02/AOL-L...
Look how strikingly bland and empty that new one is. It means nothing, says nothing, commands no lasting memory. The perfect representation of the world's largest, most soulless content farm.
Truly: perfect.
As in "Thinking about AOL? Stop right there...".