I have I have had Kubuntu 8.10 (Intrepid) on one of my machines for a month or so. I really miss baghira, which makes linux look at much like OSX as linux can look. Alas, there will be no baghira for QT4. I thought I'd try out cloudcity (or bespin, I can't figure out what the real name is), written by the same guy who wrote baghira. It's not an OSX clone (boo), it's still early code, and you'll have to compile your own, but it's not hard. Here's what I did:

First, get the necessary development packages installed:

$ sudo apt-get install build-essential cmake kdebase-dev kdelibs5-dev libplasma-dev kdebase-workspace-dev subversion

There is quite a bit of stuff to download and install here, so it's gonna take a few minutes. After it's done, get cloudcity out of subversion:

$ svn co https://cloudcity.svn.sourceforge.net/svnroot/cloudcity

This will make a directory called `cloudcity` wherever you are.

$ cd cloudcity
$ bash configure

Yes the configure script needs bash..... it will likely break if you just do `./configure`

$ cd build
$ make

It will compile, and you'll see lots of warnings.

$ sudo make install

Now you can go to System Settings and Bespin will be a choice for window decorations and widget styles.

Enjoy.