For Full details go to the-grey-man.com
Simply I have tweaked the admin backend of a 1.5.2 install to make it look more like 1.6.
I only made changes to two files: wp-admin.css and admin-header.php. I haven't added any of the Ajax stuff or changed any of the admin backend other than the header and css.
I am not providing any support for this. I simply don't have the spare time to deal with any problems I'm afraid to say but they shouldn't be any major problems that I can foresee.
It might still needs some tweaks to the css to make it look a little better but 98% of it looks right.
If someone else wants to tweak it some more feel free.
The files are provided as is, with NO WARRANTY whatsoever.
As always use at your own risk.