Ray where can I send you link as its a confidential project for the moment being at least.
I don;t think its a php problem. In the "Admin' template no problems with IE8. When using public, something is not working properly and i believe it has to do with the <div> tags in public template.
I remember similar problem when IE7 went out. Firefox was showing it normaly the <div>s but IE7 had some problems when mixing them up. Then the usage of "clearRight/ClearLeft/ClearBoth" went popular as solution. I checked your code in front end since in general im tweaking everyhing, and u use the clearboth etc stuff in there. It seems that in IE8 in the "details.php" all the content starting from the ShortDescription till the fullDesciption + is pressed down and leaves a big white space and ofc a big height difference between these layers and the top level content, image+rest in the grey box.
If you click the compatibility view it works properly. I think it has to do with Div interpretation again.
Im getting pissed allways when a new IE release pops out.
By the way i got it in an Editable Region but shouldn't mater.