It looks like there will be no theme overhaul in Ubuntu 8.10, but a number of nice themes and concepts have been proposed. I’ve been using one of these themes, called Dust.
Dust controls and window borders:

Dust Sand controls and Dust window borders:

Dust requires a very recent version of the Murrine theme engine. Download and install the package for your system:

• Ubuntu 8.04: i386, amd64
• Ubuntu 8.10: i386, amd64

Head to the download page on Launchpad for the Dust theme. Download the dust and dust-extras tar.gz archives. Drag and drop them into the System->Preferences->Appearance->Themes window to install.
Select the Dust theme to apply it. To select one of the extra themes, click Customize, and select one of the other Dust window borders and controls.
I’ve been using the Dust Sand controls and Dust window borders for a while, I’m not too keen on the dark toolbars in the main Dust controls.

[via tombuntu.com]