I used this script (as root) to fix those permissions:
You can adapt it to your particular setup. Also, note that /var/log/* stuff will still be created with wrong permissions (at least according to msec) even after running the script. Something in the cron scripts I guess but I have no time to dig deeper...
Thanks a lot, I'll give it a try next. I have an additional question about that : do you think the changes done on the part of the script that don't belong to /var/log will be fixed for long, or that it may change fast again according to whatever will be updated ?
I will have a few more questions, about little weirdies in the Gnome version... I'll open a new thread about that.