No Group access control!? (v1.5)

I've just spotted that I do not have any Group access permissions coming up in my v1.5 install. Is this a known problem or is it just my site? I create a group, start a new blog (for example) but the access controls as still just the defaults. I have a test 1.6 site and it works OK there.

Is there a fix for this or do I have to upgrade to 1.6?