I gave up on the AjaxControlToolkit's Calendar Extender...I just couldn't wait any longer. 

 I found a free control toolkit that does the job for me...eXcentrics World's custom server controls (http://www.eworldui.net/).  This is a free download that includes a calendar popup control.  I created a set of skins and styles that mimic the look and feel of the AjaxControlToolkit's Calendar Extender.

 As a side note, this control set also includes a collapsable panel which I think is better than the AjaxControlToolkit's.