I have a similar issue with the banshee and firestarter icon backgrounds not matching the ambiance or radience themes, but being fine under the other themes. Also the font for the drop-down list for skype icon seems to colour itself the same colour as the theme, making it impossible to read until you hover your mouse pointer over each item in the list to highlight it. Again, this only is an issue with the default themes.
I have a similar issue with the banshee and firestarter icon backgrounds not matching the ambiance or radience themes, but being fine under the other themes. Also the font for the drop-down list for skype icon seems to colour itself the same colour as the theme, making it impossible to read until you hover your mouse pointer over each item in the list to highlight it. Again, this only is an issue with the default themes.