I was reading my Google+ stream the other day when I saw this post from Fab at Linux Outlaws:
X.org server allows anyone to unlock computer
It appears that there are a few distros that may be effected by this. I checked my Mint 12 install and noticed that it did not have this flaw. It appears that there should be fixes out for this, so just make sure you are updated if you are running the flawed verion.