Gnome (as well as KDE or XFCE) show them on the right of the window title by default.
Historically, Microsoft could not simply copy all of Macitoshs interface so they "invented something new". Buttons to minimize, maximize and close the window are shown on the right of the title bar.
OK, it's different, but on second thought, it is stupid as well. On a Mac (as on my Linux box) everything having to do with commands is in the top left corner (general menus, window menues, etc.). So why move the mouse to the far left of a page to manpulate window controls?
Cut a long monologue short: How to get the buttons from right to left?
gconf-editorSearch for the key:
/apps/metacity/general/button_layoutReplace the colon right to menu with a comma and place the colon at the end of the line. You can place the colon any place you want to separate left from right buttons.
I have done this on my machines and the theme now looks perfect.