I just recently installed Ubuntu 10.4 LTS and set appearance to use the ambiance theme.
The window border buttons were on the left though by default.
Now, I'm not a fluent Mac user, so I prefer having those on the right.
It proved to be really simple to do so: Hit <alt><f2>, type
gconf-editorand hit <enter>. Navigate to apps > metacity > general and edit the item
button_layoutSimply put the colon ":" on the left side of the string instead of the right side to set the buttons to be on the right side of the window border.
You can also modify the order of the buttons by modifying the order of the "maximize,minimize,close" string.