If you are designing custom master pages for a SharePoint 2007 site, be sure to make the width of your Quick Launch bar (a.k.a. left navigation bar) a minimum of 165 pixels. Otherwise the calendar control in an Events list will go over your allowed width and you will have to rework your design to accommodate the 'Today is' date.
The issue lies with the lower portion of the calendar control that lists the current date. Your width needs to accommodate the longest possible value:
Today is:
Wednesday, November 30, 2007