Cakestyle is a stylesheet that is designed to be used with the default CakePHP configuration.
Just place the updated stylesheet in app/webroot/css/ and off you go.
The stylesheet is found here.
Of course things are made more clear with some screenshots, so here we go:
This is the default CakePHP screen after installation, with this Cakestyle:
Compared to the default layout it looks way better, but i may be biased ;) :
If you have any additions or comments, they are more then welcome!