WordPress Site Not displaying properly in Internet Explorer (IE)

I had a client contact me today, informing me that their site wasn’t displaying properly in IE10, not like it used to.  The calendar (monthly and upcoming events) were not displaying properly and the media library was coming up blank!?  Why?!

After doing some basic troubleshooting, I was able to determine it wasn’t a IE10 issue, but rather a IE issue.  IE’s Compatibility View appears to break things.  It would seem that it is critical to have the Compatibility View disabled when on WordPress sites to get the proper visualization.

Case and Point:
With Compatibility View Enabled

WordPress Calendar with IE Compatibility Enabled

With Compatibility View Disabled

WordPress Calendar with IE Compatibility Disabled

One more reason not to used internet Explorer altogether.  Better off with an alternate browser such as Mozilla Firefox, Google Chrome, Opera, …

This also worries me because I cannot control how general web surfers have their browser configured, so how many visitors to this site, or any other site, aren’t getting the proper user experience?