Here is a QtCurve theme, colour scheme and Aurorae window theme for KDE4, made to look like Ambiance for Ubuntu. The idea is to get a consistent look between GNOME/GTK and KDE4/Qt appsInstructions:
Make sure you have the QtCurve theme engine installed, then go to System Settings>Application Appearance>Style and select "QtCurve" for the widget style. Select "Configure" and import the Ubuntu-Ambiance.qtcurve file.
Load the colour scheme in System Settings>Application Appearance>Colours and "Import Scheme".
Copy the Ubuntu-Ambiance directory to ~/.kde/share/apps/aurorae/themes/ and select in System Settings>Workspace Appearance>Window Decorations.Notes:
If you use Ubuntu then you can make GTK apps use the ambiance theme by running "gnome-settings-daemon" within KDE4. You can also use the Humanity icon theme, which will show up in System Settings>Application Appearance>Icons
Make sure the GTK+ theme is set to QtCurve and KDE applies it's colour settings to non GTK apps. This is make the theme render seamless between GTK and Qt/KDE apps.
Ubuntu Ambiance Plasma theme [link]