I was affected (fortunately, the private entry that was modified and made public was nothing that could cause distress, just confusion -- I've been tracking my progress on a puzzle site), and if you happened to read that entry in my journal once it was made public, you might be also.
If you were affected, you will see four boxes with scroll bars and the word "Sorry" at the bottom of one or more recent entries.
According to LJ News, this exploit did not actually compromise passwords, nor would it have infected your computer. However, you may wish to take reasonable steps to protect your password and confirm that your computer is clean.