“Display Intranet Sites in Compatibility View”, or, WTF happened to my webapp???

My project uses a lot of HTML5/CSS3/JavaScript goodies.  It works well and looks awesome… in Chrome 10 and Firefox 4.  Our User Experience designer tells me it works well and looks awesome in Safari, too.

Say, which browser is missing from the lists I just mentioned?  Right!  The very one which is our official platform. Like my boss says, “if it ain’t working on IE8, it ain’t working.”  If I was a real web designer, and not a poseur wanna-be services developer, I’d wake up in cold sweats at night with those words echoing in my ear!