Today I installed Openoffice 3.0 in my Ubuntu Hary, (but I used bittorrent ;-) )
I wanted to insert a non-breaking space by pressing <Ctrl>+<Space>. That did not work. However the answer was easy:
First I tried to insert it per Menu: Insert > Formatting Mark > Nonbreaking space. Oh, ther is a new shortcut: <Ctrl>+<Shift>+<Space>.
Here you can read why they changed the shortcut. (same key combination on every OS)