Thanks to our first comment HTML abuser, I've had to strip div and table tags from people using the Default filter (previously named "BBCode+Smilies") on comments or posted entries. Tables are still accessible with a new (and even easier) syntax. See the table demo page for further instructions. I have also reduced some of the abilities of the WikiText input filter, and gone through and cleaned up the filters in a general sense.

To the best of my knowledge, this only affected one existing entry, which I have fixed by hand. Core users and guest bloggers still have access to additional formats that allow these restrictions to be bypassed.